The overall aim of research in our laboratory is the elucidation of the factors underlying the hormonal responsiveness of human cancers. This work is focused primarily on the role of steroid hormone receptors and their coregulators. We are currently defining the programs of gene expression controlled by steroid hormones and their receptors in relevant cell types using a combination of approaches including gene expression profiling and "ChIP-chip." In addition we are testing the hypothesis that coregulators act as mediators of the differential activity of receptors bound by agonist and antagonist ligands. In addition we are asking whether alterations in coregulator function play a role in both resistance to endocrine therapy and in carcinogenesis. This work has focused primarily on the role of estrogen receptor and its coregulators in breast cancer and androgen receptor and its coregulators in prostate cancer.