ESR1 and prostate cancer: Based on the recent findings that ER ligands can directly modulate androgen actions in prostate cancer cells in a receptor-ligand and receptor-isoform specific manner (6,7,24) and that androgens can directly stimulate endothelial cell proliferation in a gender-specific manner (25,30), we have compared the effects of various ER ligands on the modulation of androgen actions between endothelial HAECs and prostate cancer cells in the present study.