To determine the effects of various ER ligands on the regulation of DHT-induced cell proliferation in endothelial and prostate cancer cells, endothelial HAECs or prostate cancer cells were seeded in 96-well plates and treated with DHT plus or minus various concentrations of αE2, βE2, DES, ICI, genistein, and tamoxifen (Figs. 1–3) for 48 or 72 h, respectively. This evidence concerns the gene ESR1 and Familial prostate cancer.