ABSTRACT
Differential gene expression is a key component of many complex phenomena includ ing cellular development, differentiation, maintenance, and injury or death. In fact, the subset of genes that is being expressed determines to a large extent the phenotype of a cell. Also, a loss of control of differential gene expression underlies many dis ease states, not the least of which is cancer. The identification of genes that are being
expressed in one cell type versus another (e.g., control versus treated, tumor versus normal) can help in explaining the function of those genes as well as lend insight into the system being examined. For this reason, the identification of differentially expressed genes has been pursued for diverse stimuli such as responses to biologic programs (developmental and circadian cues), physical agents (e.g., UV irradiation, x rays), and chemical agents (hormones and xenobiotics). In fact, over 300 examples of these pursuits can be found in the literature (1) and have resulted in a much greater understanding of cellular biology and our responses to physical and chemical insult.
