Genomics. Microarrays--guilt by association.

DNA microarray analysis has provided a wealth of data on global patterns of gene expression but has yet to deliver on its early promise of identifying networks of interacting gene products. In his Perspective, Quackenbush discusses new work (Stuart et al.) that uses evolutionary conservation of gene expression patterns in yeast, worm, fruit fly, and human in an attempt to identify functionally related groups of genes.