ABSTRACT
Differential expression is a useful tool for the analysis of DNA microarray data. However, and in spite of the fact that it can be applied to a large number of genes, differential analysis remains within the confines of the old one-gene-at-a-time paradigm. Knowing that a gene’s behavior has changed between two situations is at best a first step. In a cancer experiment, for instance, a significant change could be associated with a direct causal link (activation of an oncogene), a more indirect chain of effects (signalling pathway), a non-specific related phenomena (cell division), or even a spurious event completely unrelated to cancer (“noise”).
