Within the fold: assessing differential expression measures and reproducibility in microarray assays

Fold-change' cutoffs have been widely used in microarray assays to identify genes that are differentially expressed. More accurate measures are required to identify high-confidence sets of genes with biologically meaningful changes in transcription. A general procedure for analyzing cDNA microarray data is proposed and validated. It is shown that pooled reference samples should be based not only on the expression of individual genes in each cell line but also on the expression levels of genes within cell lines.