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Nucleic Acids Research, 2003, Vol. 31, No. 4 e15
© 2003 Oxford University Press

Summaries of Affymetrix GeneChip probe level data

Rafael A. Irizarry*, Benjamin M. Bolstad1, Francois Collin2, Leslie M. Cope3, Bridget Hobbs4 and Terence P. Speed4,5

Department of Biostatistics, Johns Hopkins University, Baltimore, MD 21205, USA, 1 Biostatistics Group, University of California, Berkeley, CA, USA, 2 Gene Logic Inc., Berkeley, CA, USA, 3 Mathematical Sciences Department, Johns Hopkins University, Baltimore, MD, USA, 4 Division of Genetics and Bioinformatics, WEHI, Melbourne, Australia and 5 Department of Statistics, University of California, Berkeley, CA, USA

*To whom correspondence should be addressed. Tel: +1 410 614 5157; Fax: +1 410 955 0958; Email: rafa{at}jhu.edu

Received October 8, 2002; Revised and Accepted November 25, 2002


    ABSTRACT
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
High density oligonucleotide array technology is widely used in many areas of biomedical research for quantitative and highly parallel measurements of gene expression. Affymetrix GeneChip arrays are the most popular. In this technology each gene is typically represented by a set of 11–20 pairs of probes. In order to obtain expression measures it is necessary to summarize the probe level data. Using two extensive spike-in studies and a dilution study, we developed a set of tools for assessing the effectiveness of expression measures. We found that the performance of the current version of the default expression measure provided by Affymetrix Microarray Suite can be significantly improved by the use of probe level summaries derived from empirically motivated statistical models. In particular, improvements in the ability to detect differentially expressed genes are demonstrated.


    INTRODUCTION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Affymetrix GeneChip arrays (1) are used by thousands of researchers worldwide. The number of publications in scientific journals based on data produced using this technology is proof of its success. To probe genes, oligonucleotides of length 25 bp are used (2). Typically, a mRNA molecule of interest (usually related to a gene) is represented by a probe set composed of 11–20 probe pairs of these oligonucleotides. Each probe pair is composed of a perfect match (PM) probe, a section of the mRNA molecule of interest, and a mismatch (MM) probe that is created by changing the middle (13th) base of the PM with the intention of measuring non-specific binding. For simplicity, in this paper we will refer to the probed DNA molecules of interest as genes. After scanning the arrays hybridized to labeled RNA samples, intensity values PMij and MMij are recorded for arrays i = 1,..., I and probe pairs j = 1,..., J, for any given probe set.

To define a measure of expression representing the amount of the corresponding mRNA species it is necessary to summarize probe intensities for each probe set. Several model-based approaches to this problem have been proposed. We have developed an effective expression measure motivated by a log scale linear additive model. This summary statistic is referred to as the log scale robust multi-array analysis (RMA).

Using carefully prepared test data we can define tasks where we have an expectation of correct results. We used data from spike-in and dilution experiments to conduct various assessments on the RMA expression measure and two widely used competitors. Specifically, we compared the measures of expression according to three criteria of special interest to biomedical researchers. Any complete analysis of an expression measure should include at least assessments of the measure’s precision, consistency of fold change, and specificity and sensitivity of the measure’s ability to detect differential expression. We performed these assessments and demonstrated the substantial benefits of using the RMA measure to users of the GeneChip technology.


    MATERIALS AND METHODS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The first version of Affymetrix’s analysis software (3) used an average over probe pairs of the differences PMij MMij, j = 1,..., J, for each array i. A robust average was used to protect against outlier probes. Summary statistics, such as this average difference (AD), are motivated by underlying statistical models. A model for AD is PMijMMij = {theta}i + {epsilon}ij, j = 1,..., J. The expression quantity on array i is represented with the parameter {theta}i. AD is an appropriate estimate of {theta}i if the error term {epsilon}ij has equal variance for j = 1,..., J. However, the equal variance assumption does not hold for GeneChip probe level data, since probes with larger mean intensities have larger variances (4). In the latest version of their software (5), Affymetrix uses a log transformation that is successful at reducing the dependence of the variance on the mean. Specifically, the MAS 5.0 signal is defined as the anti-log of a robust average (Tukey biweight) of the values log(PMijCTij), j = 1,..., J. To avoid taking the log of negative numbers, CT is defined as a quantity equal to MM when MM < PM, but adjusted to be less than PM when MM >= PM, which in general occurs for about one-third of all probes (4,6). A model for MAS 5.0 is log(PMij CTij) = log({theta}i) + {epsilon}ij, j = 1,..., J.

A recent paper (7) reported that variation of a specific probe across multiple arrays could be considerably smaller than the variance across probes within a probe set. In the log2 scale, the between-array standard deviation (SD) is in general five times smaller than the within-probe set SD (4,7). To account for this strong probe affinity effect, a multiplicative model, PMijMMij = {theta}i{phi}j + {epsilon}ij, i = 1,..., I, j = 1,..., J, was proposed (7). The probe affinity effect is represented by {phi}j. For analyses where multiple arrays are available a model-based expression index is defined as the maximum likelihood estimate (under the assumption that the errors follow a normal distribution) of the expression parameters {theta}i. This estimate will depend on the probe affinity effects {phi}j, which we can estimate if we have enough arrays. The software package dChip (http://www. biostat.harvard.edu/complab/dchip/) can be used to fit this model and obtain what we refer to as the dChip expression measure. Outlier probe intensities are removed as part of the estimation procedure (7).

Using data from a spike-in experiment (described in more detail below) we found that appropriately removing background and normalizing probe level data across arrays results in an improved expression measure motivated by a log scale linear additive model. The model can be written as T(PMij) = ei + aj + {epsilon}ij, i = 1,..., I, j = 1,..., J, where T represents the transformation that background corrects, normalizes, and logs the PM intensities, ei represents the log2 scale expression value found on arrays i = 1,..., I, aj represents the log scale affinity effects for probes j = 1,..., J, and {epsilon}ij represents error as above. Notice that this is an additive model for the log transform of (background corrected, normalized) PM intensities. It is quite different from the additive model in PMMM that was found unsatisfactory in Li and Wong (7), most likely because of the very strong mean variance dependence that would be present in such an additive model. A robust linear fitting procedure, such as median polish (8), was used to estimate the log scale expression values ei. The resulting summary statistic is referred to as RMA. The normalization and background correction procedures used are reported elsewhere (4,9). Recent results (4,10) suggest that subtracting MM as a way of correcting for non-specific binding is not always appropriate. It is possible that information about non-specific binding is contained in the MM values, but empirical results demonstrate that mathematical subtraction does not translate to biological subtraction. We have found that, until a better solution is proposed, simply ignoring these values is preferable.

There is no gold standard to compare and test summaries of probe level data. For this reason, data from spike-in experiments have been used to assess the technology and to motivate normalization procedures (1,11,12). In a recent paper (13) a dilution/mixture experiment was used to compare existing expression measures. In a similar way, we used data from spike-in and dilution experiments to conduct various assessments on the MAS 5.0, dChip and RMA expression measures. Specifically, we compare the measures of expression according to three criteria: (i) the precision of the measures of expression, as estimated by standard deviations across replicate chips; (ii) the consistency of fold change estimates based on widely differing concentrations of target mRNA hybridized to the chip; (iii) the specificity and sensitivity of the measures’ ability to detect differential expression, presented in terms of receiver operating characteristic (ROC) curves.

For the dilution study (http://qolotus02.genelogic.com/datasets.nsf/), two sources of cRNA, human liver tissue and a central nervous system cell line (CNS), were hybridized to human arrays (HG-U95A) in a range of dilutions and proportions (4). We studied data from six groups of arrays that had hybridized liver and CNS cRNA at concentrations of 1.25, 2.5, 5.0, 7.5, 10.0 and 20.0 µg total cRNA. Five replicate arrays were available for each generated cRNA (n = 60 total).

For the spike-in studies, different cRNA fragments were added to the hybridization mixture of the arrays at different pM concentrations. The cRNAs were spiked-in at a different concentration on each array (apart from replicates) arranged in a cyclic Latin square design with each concentration appearing once in each row and column. All arrays had a common background cRNA. We used data from two different studies, one from Affymetrix (http://www.affymetrix.com/analysis/download_center2.affx) where 14 human genes were spiked-in at concentrations ranging from 0 to 1024 pM and one from GeneLogic (http://qolotus02.genelogic.com/datasets.nsf/) where 11 control cRNA fragments were spiked-in at concentrations ranging from 0 to 100 pM.

The GeneLogic spike-in experiment consists of a number of arrays each hybridized to samples with suitable concentrations of 11 different cRNA fragments added to a hybridization mixture consisting of cRNA from the same AML tissue. The 11 control cRNAs were BioB-5, BioB-M, BioB-3, BioC-5, BioC-3 and BioDn-5 (all Escherichia coli), CreX-5 and CreX-3 (phage P1), and DapX-5, DapX-M and DapX-3 (a Bacillus subtilis gene) (11,14,15). The cRNA were chosen to match the target sequence for each of the Affymetrix control probe sets. For example, for DapX (a B.subtilis gene), the 5', middle and 3' target sequences (identified by DapX-5, DapX-M and DapX-3) were each synthesized separately and spiked-in at a specific concentration. Thus, for example, DapX-3 target sequence may be added to the total hybridization solution of 200 µl to give a final concentration of 0.5 pM. The 11 control cRNAs were spiked-in at a different concentration on each array (apart from replicates). The 12 concentrations used were 0.5, 1, 1.5, 2, 3, 5, 12.5, 25, 37.5, 50, 75 and 100 pM, and these were arranged in a 12 x 12 cyclic Latin square, with each concentration appearing once in each row and column. The 12 combinations of concentrations used on the arrays were taken from the first 11 entries of the 12 rows of this Latin square. Three replicated hybridizations were carried out for each combination of concentrations of the spiked-in material.

The Affymetrix spike-in experiment was done in a similar fashion. It consists of a series of human genes spiked-in at known concentrations. They represent a subset of the data used to develop and validate the MAS 5.0 algorithm. The Latin square consists of 14 spiked-in gene groups in 14 array groups. The concentration of the 14 groups in the first array group are 0, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 and 1024 pM. Each subsequent array group rotates the spike-in concentrations by one group, i.e. array group 2 begins with 0.25 pM and ends at 0 pM, on up to array group 14, which begins with 1024 pM and ends with 512 pM. There were three replicates for each concentration combination, except for two combinations for which 12 replicates were formed.

The results presented in the figures and tables were ob tained using the R environment (16), which can be freely downloaded from http://www.r-project.org/. All the data (cel files) containing the probe level intensities are available on the World Wide Web as stated above. To obtain the MAS 5.0 expression measures these files were processed with MAS 5.0 software. The software package dChip (http://www. biostat.harvard.edu/complab/dchip/) was used to obtain the dChip measures. The default PM-only model version was used. The RMA measures were computed using the Methods for Affymetrix Oligonucleotide Arrays R package (17), which is freely available on the World Wide Web (http://www. bioconductor.org).


    RESULTS
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
A common measure of precision used in the literature to compare replicate arrays is the squared correlation coefficient (R2). For the dilution data we computed average R2 over all 120 pairs of replicates (two tissues x six concentrations x 10 different pairs in each group of five replicates). We found that RMA outperformed dChip, which in turn outperformed MAS 5.0, with their average R2 values being 0.995, 0.993 and 0.990, respectively. The differences between the R2 averages are statistically significant. However, because of the strong probe affinity effect, GeneChip arrays will in general have R2 values close to 1, even for non-replicate arrays. The gene-specific log expression SD across replicates is a more informative assessment. We computed the SD of the expression values (log2 scale) across the five replicates in each of the six concentration groups. Smooth curves were then fitted to scatter plots of these SD values versus average expression value (log2 scale) (Fig. 1). This plot showed that RMA had a smaller SD at all levels of expression, with the SD for RMA being one-tenth that of the SD for MAS 5.0 and one-fifth of that for dChip at very low levels of average expression (1–2 on the log2 scale). To ensure that signal detection was not sacrificed for the gains in noise reduction, we examined the ability of the expression measures to detect the increase in cRNA across the concentration groups. As a summary of signal detection we computed the average, over all genes, of the expression versus concentration lines on the log–log scale (second and third rows in Table 1). Since every fold increase in concentration of the target sample should give rise to the same fold increase in an expression measure, a line fitted on the log–log scale should have slope 1. For reasons we don’t understand, all three measures lead to slopes well below 1, but on this criterion, RMA and MAS 5.0 performed similarly. dChip had a slightly smaller signal. This assessment demonstrated that RMA has similar accuracy but better precision than the other two summaries.



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Figure 1. The smooth curves shown were fitted to the scatter plots of SD versus average of log (base 2) expression for each gene using MAS 5.0, dChip and RMA on the dilution data. All genes for all six concentrations in liver and CNS groups were used.

 

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Table 1. Summary statistics from dilution experiment (details described in the text)
 
A basic application of the GeneChip technology is to study differences in gene expression between different RNA samples. Observed fold change in expression measures is used to assess differential expression (3). While the Affymetrix protocol calls for 15 µg of RNA, in practice the amount of target mRNA available for the hybridization reactions can differ greatly depending on the cells or tissue type under study. In some cases the available RNA will be amplified, and in others the hybridization will be carried out with <15 µg. It is desirable to have estimated fold changes in expression largely independent of the amount of target mRNA used. For an extreme example, suppose that one series of experiments is done with 20 µg of RNA in each hybridization, and another series is identical, but uses just 1.25 µg of RNA. Ideally, the answers should be very similar. For each gene we computed fold change estimates between the liver and CNS samples using the 10 arrays in the 1.25 µg concentration group for each of the three expression measures. We then computed estimates using the arrays in the 20 µg concentration group. Because fold change is a relative measure, estimates should be independent of the amount of RNA that is hybridized to the arrays. Log (base 2) fold change estimates of gene expression between liver and CNS samples computed from arrays hybridized to 1.25 µg of cRNA were plotted against the same estimates obtained from arrays hybridized to 20 µg for all three measures (Fig. 2). The correlation of fold change estimates from the different concentrations (Table 1) demonstrated that RMA and dChip provided more consistent estimates than MAS 5.0. RMA was slightly better than dChip. Using MAS 5.0 (Fig. 2A), 1223 genes had at least a 2-fold discrepancy (shown with larger dots) between the two fold change estimates. For dChip there were 302 (Fig. 2B) and for RMA (Fig. 2C) there were only 22. This assessment demonstrated that RMA provides more consistent estimates of fold change.





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Figure 2. (A) Log (base 2) fold change estimates of gene expression between liver and CNS samples computed from arrays hybridized to 1.25 µg of cRNA using MAS 5.0 plotted against the same estimates obtained from arrays hybridized to 20 µg. Genes demonstrating 2- to 3-fold inconsistencies are shown with squares. Genes demonstrating inconsistencies larger than 3-fold are shown with circles. (B) As (A) but using dChip. (C) As (A) but using RMA.

 
A typical application of GeneChip technology is finding genes that are differentially expressed in different tissues. Successful fold change analysis will detect all and only genes that are differently expressed due to biological variation. Because in the spike-in experiments arrays were hybridized to the same background, successful differential expression analyses should identify only the spiked-in genes as being differentially expressed. The absence of a batch mode in MAS 5.0 and dChip made running comparisons for all pairs prohibitive due to time. We therefore chose 10 pairs of arrays at random from both Affymetrix and GeneLogic spike-in studies. For each of these pairs we computed estimates of fold change using the three expression measures. Then, for a large range of cut-off values we computed the number of false positives (non-spiked-in genes with fold change estimates larger than the cut-off) and the number of true positives (spiked-in genes with fold change estimates larger than the same cut-off). ROC curves were created by plotting the true positive rates (sensitivity) versus false positive rates (1 – specificity). The true positive rates were estimated for the filtering operation, Observed Fold Change > cut-off, for a large range of cut-off values, by calculating the proportion of genes spiked-in at different concentrations that satisfy the filtering criterion. False positive rates were calculated in a similar way by computing the proportion of non-spiked-in genes that satisfy the filtering criteria. Areas under ROC curves can be used to compare specificity and sensitivity of competing tests. The fact that the RMA curves dominated the dChip and MAS 5.0 curves demonstrated that the differential expression calls obtained with RMA have higher sensitivity and specificity than those obtained with the other two measures (Fig. 3A and B). The true fold changes resulting from our random choice of pairs ranged from 3/2 to 1024. The task of detecting fold changes much larger than 2 might be considered less important than that of reliably detecting changes 2-fold or less, so we chose 10 pairs where the true fold changes were exactly 2 and repeated the analysis. The superiority of RMA appears even greater in this assessment (Fig. 3C). For comparisons of two arrays, Affymetrix software provides an alternative to fold change analysis based on the P value of a non-parametric test statistic (5). Test statistics can be created for RMA and dChip based on estimates of standard error obtained from probe level data (4,7). We repeated the above analysis for the test statistic and found the Affymetrix’s P value approach to work as well as the test statistic based on RMA and better than dChip’s version (Fig. 3D and E). However, Affymetrix’s P value analysis can only be used when comparing two arrays. We performed fold change analyses on two sets of 12 arrays with the same spiked-in concentrations and found RMA to have almost perfect sensitivity and specificity (Fig. 3F). In this comparison, dChip performed almost as well as RMA and significantly better than MAS 5.0. This assessment demonstrated that using RMA provides higher specificity and sensitivity when using fold change analysis to detect differential expression.








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Figure 3. (Previous page and above) ROC curves for spike-in experiments. (A) For 10 pairs of arrays, chosen at random from the Affymetrix spike-in experiment, true positive rates (sensitivity) are estimated for the filtering operation, Observed Fold Change > cut-off, for a large range of cut-off values, by calculating the proportion of genes spiked-in at different concentrations that satisfy the filtering criterion. False positive rates (1 – specificity) are calculated in a similar way by computing the proportion of non-spiked-in genes, which satisfy the filtering criteria. (B) As (A) but using the GeneLogic spike-in experiment. (C) As (A) but selecting 10 comparisons for which the fold changes of spike-in concentrations are 2. (D) As (A) but using the filtering operation test statistic > cut-off. We used the software default test statistics for MAS 5.0 and dChip. (E) As (D) but using the GeneLogic spike-in experiment. (F) As (A) but comparing the average fold changes obtained from two sets of 12 replicate arrays.

 
To understand why fold change analysis using RMA has better sensitivity and specificity we looked at Mg = log2(Yg/Xg) versus Ag = log2{surd}XgYg = (logXg + logYg)/2, (MvA) plots for expressions Xg and Yg from two arrays being compared for all genes, g = 1,..., G. Log scale scatter plots of Yg versus Xg are commonly seen in the literature. MvA plots are 45° rotations of these scatter plots (18). We found MvA plots useful because log fold change (the quantity of most interest) is represented on the y-axis and average absolute log expression (another quantity of interest) on the x-axis. We selected one array from one of the Affymetrix spike-in experiments to use as a reference and then computed Mg and Ag for the comparisons of that array with all other arrays in the experiment using MAS 5.0 (Fig. 4A), dChip (Fig. 4B) and RMA (Fig. 4C). In these plots, the colored numbers represent the log (base 2) fold change in concentrations of all 14 spiked-in genes. Each distinct fold change is represented with a different color as a visual aid. The -{infty} and {infty} represent fold changes with a zero in the numerator or denominator, respectively. The red points represent non-spiked-in genes with a fold change larger than 2. Except for the colored numbers, including {infty}, genes should have log fold changes of 0. The fact that using RMA resulted in plots with fewer red points demonstrated that its smaller variance, especially for genes with lower absolute expression (Fig. 4A–C) resulted in better detection capability of genes spiked-in at different concentrations in the different arrays. Most of the genes having log fold changes of 2 when 0 was expected (red points in Fig. 4A) for MAS 5.0 were due to this large variance at the low end. Color box plots (Fig. 5) of fold change estimates demonstrated that RMA produces fold changes closer to 1 for genes that are not changing than those for MAS 5.0, with those for dChip being in between. In particular, the interquartile ranges of log2 fold change for equivalently expressed genes were 0.92, 0.22 and 0.19 for MAS 5.0, dChip and RMA, respectively.





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Figure 4. MvA plots (described in the text) for Affymetrix’s spike-in experiment. (A) For MAS 5.0, observed log (base 2) fold change (M) is plotted against average log (base 2) expression (A) for all genes from spike-in experiment array pairs. A reference array was selected from one of the replicate spike-in experiments and compared to all other arrays in that replicate experiment. The colored numbers represent the log (base 2) fold change in concentrations of all 14 spiked-in genes. Each distinct fold change is represented with a different color as a visual aid. The –{infty} and {infty} represent fold changes with a zero in the numerator or denominator, respectively. The red points represent non-spiked-in genes with a fold change larger than 2. (B) As (A) but using dChip. (C) As (A) but using RMA.

 


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Figure 5. Box plots showing the distribution of observed fold changes for non-spiked in genes. The different colors represent the different quantiles. The relationship of color and quantile is demonstrated in the first box from the left.

 
Figures 2 and 4 also show that RMA compressed fold change estimates by 10–20% when compared to MAS 5.0. However, we believe that this modest loss of accuracy is well worth the substantial gains in precision achieved by RMA in relation to MAS 5.0. Our ongoing research is aimed at incorporating the MM intensities in such a way as to improve accuracy without sacrificing precision.


    DISCUSSION
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
We have developed a summary of Affymetrix GeneChip probe level data, RMA, which serves as a measure of gene expression and compared it to other standard measures. Through the analyses of dilution and spike-in data sets we have shown that our measure performs better than MAS 5.0 and dChip. Specifically we found that: (i) RMA has better precision; in particular, for lower expression values we found that RMA provides a greater than 5-fold reduction of the within-replicate variance as compared to dChip and MAS 5.0; (ii) RMA provided more consistent estimates of fold change; (iii) RMA provided higher specificity and sensitivity when using fold change analysis to detect differential expression. For example, Figure 3C shows that for a false positive rate of 5%, the true positive rates were as different as 5, 60 and 75% for MAS 5.0, dChip and RMA, respectively, when performing fold change analysis. This greater sensitivity and specificity of RMA in detection of differential expression provides a useful improvement for researchers using the Affymetrix GeneChip technology.


    ACKNOWLEDGEMENTS
 
We would like to thank GeneLogic and Affymetrix for the data, in particular, Uwe Scherf, Yasmin D. Beazer-Barclay and Kristen J. Antonellis (GeneLogic). We would also like to thank the R core, Bioconductor and Laurent Gautier (Technical University of Denmark) for writing great code and Ron Brookmeyer, Thomas Cappola, Sabra Klein, Scott Zeger (Johns Hopkins University), Ken Simpson, Sam Wormald (Walter and Eliza Hall Institute), Cheng Li (Harvard University) and Earl Hubbell (Affymetrix) for their insightful comments. The work of R.I. is supported by the PGA U01 HL66583.


    REFERENCES
 TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Lockhart,D., Dong,H., Byrne,M., Follettie,M., Gallo,M., Chee M., Mittmann,M., Wang,C., Kobayashi,M., Horton,H. et al. (1996) Expression monitoring by hybridization to high-density oligonucleotide arrays. Nat. Biotechnol., 14, 1675–1680.[CrossRef][Web of Science][Medline]

  2. Lipshutz,R., Fodor,S., Gingeras,T. and Lockhart D. (1999) High density synthetic oligonucleotide arrays. Nature Genet., Suppl. 21, 20–24.

  3. Affymetrix (1999) Microarray Suite User Guide, Version 4. Affymetrix, http://www.affymetrix.com/support/technical/manuals.affx.

  4. Irizarry,R., Hobbs,B., Collin,F., Beazer-Barclay,Y., Antonellis,K., Scherf,U. and Speed,T. (2003) Exploration, normalization, and summaries of high density oligonucleotide array probe level data. Biostatistics, in press.

  5. Affymetrix (2001) Microarray Suite User Guide, Version 5. Affymetrix, http://www.affymetrix.com/support/technical/manuals.affx.

  6. Naef,F., Lim,D.A., Patil,N. and Magnasco,M. (2002) DNA hybridization to mismatched templates: a chip study. Phys. Rev. E Stat. Nonlin. Soft Matter Phys., 65, 040902.[Medline]

  7. Li,C. and Wong,W. (2001) Model-based analysis of oligonucleotide arrays: expression index computation and outlier detection. Proc. Natl Acad. Sci. USA, 98, 31–36.[Abstract/Free Full Text]

  8. Tukey,J. (1977) Exploratory Data Analysis. Addison-Wesley, Reading, MA.

  9. Bolstad,B., Irizarry,R., Åstrand,M. and Speed,T. (2003) A comparison of normalization methods for high density oligonucleotide array data based on variance and bias. Bioinformatics, in press.

  10. Naef,F., Hacker,C., Patil N. and Magnasco,M. (2002) Empirical characterization of the expression ratio noise structure in high-density oligonucleotide arrays. Genome Biol., 3, RESEARCH0018.[Medline]

  11. Hill,A., Brown,E., Whitley,M., Tucker-Kellogg,G., Hunter G. and Slonim,D. (2001) Evaluation of normalization procedures for oligonucleotide array data based on spiked cRNA controls. Genome Biol., 2, RESEARCH0055.[Medline]

  12. Chudin,E., Walker,R., Kosaka,A., Wu,S., Rabert,D., Chang,T. and Kreder,D. (2001) Assessment of the relationship between signal intensities and transcript concentration for Affymetrix GeneChip® arrays. Genome Biol., 3, RESEARCH0005.

  13. Lemon,W., Palatini,J., Krahe,R. and Wright,F. (2002) Theoretical and experimental comparisons of gene expression indices for oligonucleotide arrays. Bioinformatics, 18, 1470–1476.[Abstract/Free Full Text]

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  17. Irizarry,R., Gautier,L. and Cope,L. (2003) An R package for analyses of Affymetrix oligonucleotide arrays. In Parmigiani,G., Garrett,E.S., Irizarry,R.A. and Zeger,S.L. (eds), The Analysis of Gene Expression Data: Methods and Software. Springer, in press.

  18. Dudoit,S., Yang,Y., Luu,P., Lin,D., Peng,V., Ngai,J. and Speed,T. (2002) Normalization for cDNA microarray data: a robust composite method addressing single and multiple slide systematic variation. Nucleic Acids Res., 30, e15.[Abstract/Free Full Text]


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Eukaryot CellHome page
V. Meyer, M. Arentshorst, S. J. Flitter, B. M. Nitsche, M. J. Kwon, C. G. Reynaga-Pena, S. Bartnicki-Garcia, C. A. M. J. J. van den Hondel, and A. F. J. Ram
Reconstruction of Signaling Networks Regulating Fungal Morphogenesis by Transcriptomics
Eukaryot. Cell, November 1, 2009; 8(11): 1677 - 1691.
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Genome ResHome page
R. R. Nayak, M. Kearns, R. S. Spielman, and V. G. Cheung
Coexpression network based on natural variation in human gene expression reveals gene interactions and functions
Genome Res., November 1, 2009; 19(11): 1953 - 1962.
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Am. J. Pathol.Home page
C. Pollard, M. Nitz, A. Baras, P. Williams, C. Moskaluk, and D. Theodorescu
Genoproteomic Mining of Urothelial Cancer Suggests {gamma}-Glutamyl Hydrolase and Diazepam-Binding Inhibitor as Putative Urinary Markers of Outcome after Chemotherapy
Am. J. Pathol., November 1, 2009; 175(5): 1824 - 1830.
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Plant Physiol.Home page
Y. Pang, J. P. Wenger, K. Saathoff, G. J. Peel, J. Wen, D. Huhman, S. N. Allen, Y. Tang, X. Cheng, M. Tadege, et al.
A WD40 Repeat Protein from Medicago truncatula Is Necessary for Tissue-Specific Anthocyanin and Proanthocyanidin Biosynthesis But Not for Trichome Development
Plant Physiology, November 1, 2009; 151(3): 1114 - 1129.
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Nucleic Acids ResHome page
H. Ge, M. Wei, P. Fabrizio, J. Hu, C. Cheng, V. D. Longo, and L. M. Li
Comparative analyses of time-course gene expression profiles of the long-lived sch9{Delta} mutant
Nucleic Acids Res., October 30, 2009; (2009) gkp849v1.
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J. Biol. Chem.Home page
M. Giannakis, H. K. Backhed, S. L. Chen, J. J. Faith, M. Wu, J. L. Guruge, L. Engstrand, and J. I. Gordon
Response of Gastric Epithelial Progenitors to Helicobacter pylori Isolates Obtained from Swedish Patients with Chronic Atrophic Gastritis
J. Biol. Chem., October 30, 2009; 284(44): 30383 - 30394.
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J. Neurosci.Home page
S. Horng, G. Kreiman, C. Ellsworth, D. Page, M. Blank, K. Millen, and M. Sur
Differential Gene Expression in the Developing Lateral Geniculate Nucleus and Medial Geniculate Nucleus Reveals Novel Roles for Zic4 and Foxp2 in Visual and Auditory Pathway Development
J. Neurosci., October 28, 2009; 29(43): 13672 - 13683.
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J. Neurosci.Home page
M. Gersten, M. Alirezaei, M. C. G. Marcondes, C. Flynn, T. Ravasi, T. Ideker, and H. S. Fox
An Integrated Systems Analysis Implicates EGR1 Downregulation in Simian Immunodeficiency Virus Encephalitis-Induced Neural Dysfunction
J. Neurosci., October 7, 2009; 29(40): 12467 - 12476.
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BiostatisticsHome page
A. Andrei and C. Kendziorski
An efficient method for identifying statistical interactors in gene association networks
Biostat., October 1, 2009; 10(4): 706 - 718.
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Cancer Res.Home page
B. S. Balakumaran, A. Porrello, D. S. Hsu, W. Glover, A. Foye, J. Y. Leung, B. A. Sullivan, W. C. Hahn, M. Loda, and P. G. Febbo
MYC Activity Mitigates Response to Rapamycin in Prostate Cancer through Eukaryotic Initiation Factor 4E-Binding Protein 1-Mediated Inhibition of Autophagy
Cancer Res., October 1, 2009; 69(19): 7803 - 7810.
[Abstract] [Full Text] [PDF]


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BloodHome page
H. J. M. de Jonge, E. S. J. M. de Bont, P. J. M. Valk, J. J. Schuringa, M. Kies, C. M. Woolthuis, R. Delwel, N. J. G. M. Veeger, E. Vellenga, B. Lowenberg, et al.
AML at older age: age-related gene expression profiles reveal a paradoxical down-regulation of p16INK4A mRNA with prognostic significance
Blood, October 1, 2009; 114(14): 2869 - 2877.
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Proc. Natl. Acad. Sci. USAHome page
S. W. Hong, S. M. Hong, J. W. Yoo, Y. C. Lee, S. Kim, J. T. Lis, and D.-k. Lee
Phosphorylation of the RNA polymerase II C-terminal domain by TFIIH kinase is not essential for transcription of Saccharomyces cerevisiae genome
PNAS, August 25, 2009; 106(34): 14276 - 14280.
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Cancer Res.Home page
A. Chen, I. Cuevas, P. A. Kenny, H. Miyake, K. Mace, C. Ghajar, A. Boudreau, M. Bissell, and N. Boudreau
Endothelial Cell Migration and Vascular Endothelial Growth Factor Expression Are the Result of Loss of Breast Tissue Polarity
Cancer Res., August 15, 2009; 69(16): 6721 - 6729.
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Clin. Cancer Res.Home page
A. Patino-Garcia, M. Zalacain, C. Folio, C. Zandueta, L. Sierrasesumaga, M. San Julian, G. Toledo, J. De Las Rivas, and F. Lecanda
Profiling of Chemonaive Osteosarcoma and Paired-Normal Cells Identifies EBF2 as a Mediator of Osteoprotegerin Inhibition to Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand-Induced Apoptosis
Clin. Cancer Res., August 15, 2009; 15(16): 5082 - 5091.
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Nucleic Acids ResHome page
S. Bicciato, R. Spinelli, M. Zampieri, E. Mangano, F. Ferrari, L. Beltrame, I. Cifola, C. Peano, A. Solari, and C. Battaglia
A computational procedure to identify significant overlap of differentially expressed and genomic imbalanced regions in cancer datasets
Nucleic Acids Res., August 1, 2009; 37(15): 5057 - 5070.
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Exp. Biol. Med.Home page
M. M. Walsh, H. Yi, J. Friedman, K.-i. Cho, N. Tserentsoodol, S. McKinnon, K. Searle, A. Yeh, and P. A. Ferreira
Gene and Protein Expression Pilot Profiling and Biomarkers in an Experimental Mouse Model of Hypertensive Glaucoma
Experimental Biology and Medicine, August 1, 2009; 234(8): 918 - 930.
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Am. J. Pathol.Home page
X.-Y. Wang, A. Demelash, H. Kim, S. Jensen-Taubman, E. H. Dakir, L. Ozbun, M. J. Birrer, and R. I. Linnoila
Matrilysin-1 Mediates Bronchiolization of Alveoli, a Potential Premalignant Change in Lung Cancer
Am. J. Pathol., August 1, 2009; 175(2): 592 - 604.
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JAMAHome page
A. K. Yadav, J. J. Renfrow, D. M. Scholtens, H. Xie, G. E. Duran, C. Bredel, H. Vogel, J. P. Chandler, A. Chakravarti, P. A. Robe, et al.
Monosomy of Chromosome 10 Associated With Dysregulation of Epidermal Growth Factor Signaling in Glioblastomas
JAMA, July 15, 2009; 302(3): 276 - 289.
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JCOHome page
C. Langer, G. Marcucci, K. B. Holland, M. D. Radmacher, K. Maharry, P. Paschka, S. P. Whitman, K. Mrozek, C. D. Baldus, R. Vij, et al.
Prognostic Importance of MN1 Transcript Levels, and Biologic Insights From MN1-Associated Gene and MicroRNA Expression Signatures in Cytogenetically Normal Acute Myeloid Leukemia: A Cancer and Leukemia Group B Study
J. Clin. Oncol., July 1, 2009; 27(19): 3198 - 3204.
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CVIHome page
E. K. Piper, N. N. Jonsson, C. Gondro, A. E. Lew-Tabor, P. Moolhuijzen, M. E. Vance, and L. A. Jackson
Immunological Profiles of Bos taurus and Bos indicus Cattle Infested with the Cattle Tick, Rhipicephalus (Boophilus) microplus
Clin. Vaccine Immunol., July 1, 2009; 16(7): 1074 - 1086.
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BioinformaticsHome page
C. Cheng, K. Shen, C. Song, J. Luo, and G. C. Tseng
Ratio adjustment and calibration scheme for gene-wise normalization to enhance microarray inter-study prediction
Bioinformatics, July 1, 2009; 25(13): 1655 - 1661.
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Molecular Cancer TherapeuticsHome page
T. D. Pfister, W. C. Reinhold, K. Agama, S. Gupta, S. A. Khin, R. J. Kinders, R. E. Parchment, J. E. Tomaszewski, J. H. Doroshow, and Y. Pommier
Topoisomerase I levels in the NCI-60 cancer cell line panel determined by validated ELISA and microarray analysis and correlation with indenoisoquinoline sensitivity
Mol. Cancer Ther., July 1, 2009; 8(7): 1878 - 1884.
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Plant Physiol.Home page
S.-J. Oh, Y. S. Kim, C.-W. Kwon, H. K. Park, J. S. Jeong, and J.-K. Kim
Overexpression of the Transcription Factor AP37 in Rice Improves Grain Yield under Drought Conditions
Plant Physiology, July 1, 2009; 150(3): 1368 - 1379.
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IOVSHome page
F. Mantelli, L. Schaffer, R. Dana, S. R. Head, and P. Argueso
Glycogene Expression in Conjunctiva of Patients with Dry Eye: Downregulation of Notch Signaling
Invest. Ophthalmol. Vis. Sci., June 1, 2009; 50(6): 2666 - 2672.
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Nucleic Acids ResHome page
S. Tsuchiya, M. Oku, Y. Imanaka, R. Kunimoto, Y. Okuno, K. Terasawa, F. Sato, G. Tsujimoto, and K. Shimizu
MicroRNA-338-3p and microRNA-451 contribute to the formation of basolateral polarity in epithelial cells
Nucleic Acids Res., June 1, 2009; 37(11): 3821 - 3827.
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BioinformaticsHome page
P. Geeleher, D. Morris, J. P. Hinde, and A. Golden
BioconductorBuntu: a Linux distribution that implements a web-based DNA microarray analysis server
Bioinformatics, June 1, 2009; 25(11): 1438 - 1439.
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Am. J. Pathol.Home page
H. Yu, R. McDaid, J. Lee, P. Possik, L. Li, S. M. Kumar, D. E. Elder, P. Van Belle, P. Gimotty, M. Guerra, et al.
The Role of BRAF Mutation and p53 Inactivation during Transformation of a Subpopulation of Primary Human Melanocytes
Am. J. Pathol., June 1, 2009; 174(6): 2367 - 2377.
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Nucleic Acids ResHome page
Y.-S. Lee, C.-H. Chen, C.-N. Tsai, C.-L. Tsai, A. Chao, and T.-H. Wang
Microarray labeling extension values: laboratory signatures for Affymetrix GeneChips
Nucleic Acids Res., May 1, 2009; 37(8): e61 - e61.
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Brief BioinformHome page
W. B. Langdon, G. J. G. Upton, and A. P. Harrison
Probes containing runs of guanines provide insights into the biophysics and bioinformatics of Affymetrix GeneChips
Brief Bioinform, May 1, 2009; 10(3): 259 - 277.
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Mol PlantHome page
H. Zhu, G.-J. Li, L. Ding, X. Cui, H. Berg, S. M. Assmann, and Y. Xia
Arabidopsis Extra Large G-Protein 2 (XLG2) Interacts with the G{beta} Subunit of Heterotrimeric G Protein and Functions in Disease Resistance
Mol Plant, May 1, 2009; 2(3): 513 - 525.
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Poult. Sci.Home page
S. I. Lee, W. K. Lee, J. H. Shin, B. K. Han, S. Moon, S. Cho, T. Park, H. Kim, and J. Y. Han
Sexually dimorphic gene expression in the chick brain before gonadal differentiation
Poult. Sci., May 1, 2009; 88(5): 1003 - 1015.
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BloodHome page
Y.-T. Tai, E. Soydan, W. Song, M. Fulciniti, K. Kim, F. Hong, X.-F. Li, P. Burger, M. J. Rumizen, S. Nahar, et al.
CS1 promotes multiple myeloma cell adhesion, clonogenic growth, and tumorigenicity via c-maf-mediated interactions with bone marrow stromal cells
Blood, April 30, 2009; 113(18): 4309 - 4318.
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JCOHome page
P. Mendiratta, E. Mostaghel, J. Guinney, A. K. Tewari, A. Porrello, W. T. Barry, P. S. Nelson, and P. G. Febbo
Genomic Strategy for Targeting Therapy in Castration-Resistant Prostate Cancer
J. Clin. Oncol., April 20, 2009; 27(12): 2022 - 2029.
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BloodHome page
N. A. Johnson, M. Boyle, A. Bashashati, S. Leach, A. Brooks-Wilson, L. H. Sehn, M. Chhanabhai, R. R. Brinkman, J. M. Connors, A. P. Weng, et al.
Diffuse large B-cell lymphoma: reduced CD20 expression is associated with an inferior survival
Blood, April 16, 2009; 113(16): 3773 - 3780.
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Appl. Environ. Microbiol.Home page
D. van der Veen, J. M. Oliveira, W. A. M. van den Berg, and L. H. de Graaff
Analysis of Variance Components Reveals the Contribution of Sample Processing to Transcript Variation
Appl. Envir. Microbiol., April 15, 2009; 75(8): 2414 - 2422.
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J. Neurosci.Home page
A. M. Taylor, N. C. Berchtold, V. M. Perreau, C. H. Tu, N. Li Jeon, and C. W. Cotman
Axonal mRNA in Uninjured and Regenerating Cortical Mammalian Axons
J. Neurosci., April 15, 2009; 29(15): 4697 - 4707.
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Hum ReprodHome page
S. P. Gong, H. Kim, E. J. Lee, S. T. Lee, S. Moon, H.-J. Lee, and J. M. Lim
Change in gene expression of mouse embryonic stem cells derived from parthenogenetic activation
Hum. Reprod., April 1, 2009; 24(4): 805 - 814.
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Plant Physiol.Home page
E. H. Kim, Y. S. Kim, S.-H. Park, Y. J. Koo, Y. D. Choi, Y.-Y. Chung, I.-J. Lee, and J.-K. Kim
Methyl Jasmonate Reduces Grain Yield by Mediating Stress Signals to Alter Spikelet Development in Rice
Plant Physiology, April 1, 2009; 149(4): 1751 - 1760.
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Plant Physiol.Home page
F. Lippold, D. H. Sanchez, M. Musialak, A. Schlereth, W.-R. Scheible, D. K. Hincha, and M. K. Udvardi
AtMyb41 Regulates Transcriptional and Metabolic Responses to Osmotic Stress in Arabidopsis
Plant Physiology, April 1, 2009; 149(4): 1761 - 1772.
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J. Immunol.Home page
F.-X. Hubert, S. A. Kinkel, P. E. Crewther, P. Z. F. Cannon, K. E. Webster, M. Link, R. Uibo, M. K. O'Bryan, A. Meager, S. P. Forehan, et al.
Aire-Deficient C57BL/6 Mice Mimicking the Common Human 13-Base Pair Deletion Mutation Present with Only a Mild Autoimmune Phenotype
J. Immunol., March 15, 2009; 182(6): 3902 - 3918.
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JCOHome page
A. de Reynies, G. Assie, D. S. Rickman, F. Tissier, L. Groussin, F. Rene-Corail, B. Dousset, X. Bertagna, E. Clauser, and J. Bertherat
Gene Expression Profiling Reveals a New Classification of Adrenocortical Tumors and Identifies Molecular Predictors of Malignancy and Survival
J. Clin. Oncol., March 1, 2009; 27(7): 1108 - 1115.
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haematolHome page
J. A. Hernandez, A. E. Rodriguez, M. Gonzalez, R. Benito, C. Fontanillo, V. Sandoval, M. Romero, G. Martin-Nunez, A. G. de Coca, R. Fisac, et al.
A high number of losses in 13q14 chromosome band is associated with a worse outcome and biological differences in patients with B-cell chronic lymphoid leukemia
Haematologica, March 1, 2009; 94(3): 364 - 371.
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J Exp BotHome page
B. Tauris, S. Borg, P. L. Gregersen, and P. B. Holm
A roadmap for zinc trafficking in the developing barley grain based on laser capture microdissection and gene expression profiling
J. Exp. Bot., March 1, 2009; 60(4): 1333 - 1347.
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Plant Physiol.Home page
D. Chandran, Y. C. Tai, G. Hather, J. Dewdney, C. Denoux, D. G. Burgess, F. M. Ausubel, T. P. Speed, and M. C. Wildermuth
Temporal Global Expression Data Reveal Known and Novel Salicylate-Impacted Processes and Regulators Mediating Powdery Mildew Growth and Reproduction on Arabidopsis
Plant Physiology, March 1, 2009; 149(3): 1435 - 1451.
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Cancer Res.Home page
M. J. Perugorria, J. Castillo, M. U. Latasa, S. Goni, V. Segura, B. Sangro, J. Prieto, M. A. Avila, and C. Berasain
Wilms' Tumor 1 Gene Expression in Hepatocellular Carcinoma Promotes Cell Dedifferentiation and Resistance to Chemotherapy
Cancer Res., February 15, 2009; 69(4): 1358 - 1367.
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J. Biol. Chem.Home page
V. Besnard, S. E. Wert, M. T. Stahlman, A. D. Postle, Y. Xu, M. Ikegami, and J. A. Whitsett
Deletion of Scap in Alveolar Type II Cells Influences Lung Lipid Homeostasis and Identifies a Compensatory Role for Pulmonary Lipofibroblasts
J. Biol. Chem., February 6, 2009; 284(6): 4018 - 4030.
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RNAHome page
J. Burchard, A. L. Jackson, V. Malkov, R. H.V. Needham, Y. Tan, S. R. Bartz, H. Dai, A. B. Sachs, and P. S. Linsley
MicroRNA-like off-target transcript regulation by siRNAs is species specific
RNA, February 1, 2009; 15(2): 308 - 315.
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Am. J. Respir. Cell Mol. Bio.Home page
A. J. Fischer, K. L. Goss, T. E. Scheetz, C. L. Wohlford-Lenane, J. M. Snyder, and P. B. McCray Jr.
Differential Gene Expression in Human Conducting Airway Surface Epithelia and Submucosal Glands
Am. J. Respir. Cell Mol. Biol., February 1, 2009; 40(2): 189 - 199.
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GENES CELLSHome page
D. Mariappan, J. Winkler, S. Chen, H. Schulz, J. Hescheler, and A. Sachinidis
Transcriptional profiling of CD31(+) cells isolated from murine embryonic stem cells.
Genes Cells, February 1, 2009; 14(2): 243 - 260.
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JEMHome page
O. Dienz, S. M. Eaton, J. P. Bond, W. Neveu, D. Moquin, R. Noubade, E. M. Briso, C. Charland, W. J. Leonard, G. Ciliberto, et al.
The induction of antibody production by IL-6 is indirectly mediated by IL-21 produced by CD4+ T cells
J. Exp. Med., January 16, 2009; 206(1): 69 - 78.
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J. Biol. Chem.Home page
A. P. Kaur, I. B. Lansky, and A. Wilks
The Role of the Cytoplasmic Heme-binding Protein (PhuS) of Pseudomonas aeruginosa in Intracellular Heme Trafficking and Iron Homeostasis
J. Biol. Chem., January 2, 2009; 284(1): 56 - 66.
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Neuro Oncol DukeHome page
J. G. Hodgson, R.-F. Yeh, A. Ray, N. J. Wang, I. Smirnov, M. Yu, S. Hariono, J. Silber, H. S. Feiler, J. W. Gray, et al.
Comparative analyses of gene copy number and mRNA expression in glioblastoma multiforme tumors and xenografts
Neuro-oncol, January 1, 2009; 11(5): 477 - 487.
[Abstract] [Full Text] [PDF]


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Genome ResHome page
A. S.N. Seshasayee, G. M. Fraser, M. M. Babu, and N. M. Luscombe
Principles of transcriptional regulation and evolution of the metabolic system in E. coli
Genome Res., January 1, 2009; 19(1): 79 - 91.
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BioinformaticsHome page
A. L. Asare, Z. Gao, V. J. Carey, R. Wang, and V. Seyfert-Margolis
Power enhancement via multivariate outlier testing with gene expression arrays
Bioinformatics, January 1, 2009; 25(1): 48 - 53.
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BloodHome page
E. Marston, V. Weston, J. Jesson, E. Maina, C. McConville, A. Agathanggelou, A. Skowronska, K. Mapp, K. Sameith, J. E. Powell, et al.
Stratification of pediatric ALL by in vitro cellular responses to DNA double-strand breaks provides insight into the molecular mechanisms underlying clinical response
Blood, January 1, 2009; 113(1): 117 - 126.
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Clin. Cancer Res.Home page
R. N. Jorissen, L. Lipton, P. Gibbs, M. Chapman, J. Desai, I. T. Jones, T. J. Yeatman, P. East, I. P.M. Tomlinson, H. W. Verspaget, et al.
DNA Copy-Number Alterations Underlie Gene Expression Differences between Microsatellite Stable and Unstable Colorectal Cancers
Clin. Cancer Res., December 15, 2008; 14(24): 8061 - 8069.
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DevelopmentHome page
M. Ota and H. Sasaki
Mammalian Tead proteins regulate cell proliferation and contact inhibition as transcriptional mediators of Hippo signaling
Development, December 15, 2008; 135(24): 4059 - 4069.
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Proc. Natl. Acad. Sci. USAHome page
I. Astapova, L. J. Lee, C. Morales, S. Tauber, M. Bilban, and A. N. Hollenberg
The nuclear corepressor, NCoR, regulates thyroid hormone action in vivo
PNAS, December 9, 2008; 105(49): 19544 - 19549.
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RNAHome page
F. E. Nicolas, H. Pais, F. Schwach, M. Lindow, S. Kauppinen, V. Moulton, and T. Dalmay
Experimental identification of microRNA-140 targets by silencing and overexpressing miR-140
RNA, December 1, 2008; 14(12): 2513 - 2520.
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BloodHome page
A. Rodriguez-Caballero, A. C. Garcia-Montero, P. Barcena, J. Almeida, F. Ruiz-Cabello, M. D. Tabernero, P. Garrido, S. Munoz-Criado, Y. Sandberg, A. W. Langerak, et al.
Expanded cells in monoclonal TCR-{alpha}{beta}+/CD4+/NKa+/CD8-/+dim T-LGL lymphocytosis recognize hCMV antigens
Blood, December 1, 2008; 112(12): 4609 - 4616.
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Physiol. GenomicsHome page
A. Bye, M. A. Hoydal, D. Catalucci, M. Langaas, O. J. Kemi, V. Beisvag, L. G. Koch, S. L. Britton, O. Ellingsen, and U. Wisloff
Gene expression profiling of skeletal muscle in exercise-trained and sedentary rats with inborn high and low VO2max
Physiol Genomics, November 12, 2008; 35(3): 213 - 221.
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M. A. Morris, C. W. Dawson, W. Wei, J. D. O'Neil, S. E. Stewart, J. Jia, A. I. Bell, L. S. Young, and J. R. Arrand
Epstein-Barr virus-encoded LMP1 induces a hyperproliferative and inflammatory gene expression programme in cultured keratinocytes
J. Gen. Virol., November 1, 2008; 89(11): 2806 - 2820.
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Nucleic Acids ResHome page
Y. Li, P. Hao, S. Zheng, K. Tu, H. Fan, R. Zhu, G. Ding, C. Dong, C. Wang, X. Li, et al.
Gene expression module-based chemical function similarity search
Nucleic Acids Res., November 1, 2008; 36(20): e137 - e137.
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BioinformaticsHome page
E. J. Cosgrove, Y. Zhou, T. S. Gardner, and E. D. Kolaczyk
Predicting gene targets of perturbations via network-based filtering of mRNA expression compendia
Bioinformatics, November 1, 2008; 24(21): 2482 - 2490.
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Physiol. GenomicsHome page
A. Bye, M. Langaas, M. A. Hoydal, O. J. Kemi, G. Heinrich, L. G. Koch, S. L. Britton, S. M. Najjar, O. Ellingsen, and U. Wisloff
Aerobic capacity-dependent differences in cardiac gene expression
Physiol Genomics, October 8, 2008; 33(1): 100 - 109.
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C. H. Jakobsen, G. L. Storvold, H. Bremseth, T. Follestad, K. Sand, M. Mack, K. S. Olsen, A. G. Lundemo, J. G. Iversen, H. E. Krokan, et al.
DHA induces ER stress and growth arrest in human colon cancer cells: associations with cholesterol and calcium homeostasis
J. Lipid Res., October 1, 2008; 49(10): 2089 - 2100.
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