Exposure of DU145 (p53mut, AR-) and additional prostate cancer cell lines LNCaP (p53wt, AR+) and PC-3 (p53null, AR-), increasing the doses and times of p28, suggests that cytostatic, rather than cytotoxic, activity of p28 on LNCaP and DU145 was time- and dose-dependent, decreasing the proliferation of LNCaP and DU145 cell lines by 18 and 22%, respectively. The gene discussed is AR; the disease is Familial prostate cancer.