SENP1 is a SUMO isopeptidase that plays a critical role in the development of prostate cancer. SENP1 is overexpressed in prostate cancer samples and transgenic overexpression of SENP1 in the prostate of mice leads to the development of prostatic intraepithelial neoplasia at an early age.Consistent with the model stated above, investigators have demonstrated that overexpression of SENP1 enhances androgen-receptor mediated transcription. Inactivation of SENP1 in mice by retroviral insertional mutation is embryonic lethal (e12.5-e14.5) and leads to an increase in the steady-state levels of SUMOylated forms of a number of proteins.Depletion of SENP1 levels in PC3 cells by RNAi leads to a decrease in cyclin D1 expression.Transgenic overexpression of SENP1 in the prostate of mice leads to neoplasia at an early age.All of these experiments demonstrate that SENP1 plays a crucial role in the growth and development of organisms.Reinforcing the potential role SENP1 may play in prostate cancer is the observation that SENP1 is overexpressed in many prostate cancer samples.