Cancer of the prostate is a disease of unknown etiology. The long-term goals are to identify intrinsic factors which lead to the development of prostatic carcinoma. Proposed studies are based on the idea that those factors which promote cell proliferation and affect differentiation of normal cells may become determining factors in the development of neoplasia. The specific objectives are to identify factors which affect growth and differentiation of prostatic epithelium and to determine the role of these as co-factors in carcinogenesis in the prostate. Prosposed studies will make significant contributions to our knowledge of the etiology, prevention and treatment of prostatic cancer in man.