To this end, we retro-virally expressed a non-degradable mutant form of NEDD4 (NEDD4-S347A/S348A, referred to as NEDD4-AA) or wild-type NEDD4 (NEDD4-WT) in the breast cancer cell line MDA-MB-231 and the prostate cancer cell line DU145. The gene discussed is NEDD4; the disease is prostate cancer.