The overall objective of this task order is to evaluate two selective estrogen receptor &#61538; (ER&#61538;) agonists, Prinaberel (ERB-041) and LY500307, in inhibition of androgen-dependent prostate carcinogenesis induced in the Wistar-Unilever rat by N-methy-N-nitrosourea (MNU) plus testosterone. Furthermore, this task order also requires studying the chemopreventive efficacy of these two agents in association with specific signaling pathway(s) involved in cell proliferation, differentiation, and apoptosis in prostate.