PROS1 and Familial prostate cancer: Using AR‐positive prostate cancer cell lines, we showed that MA inhibited AR expression in LNCaP and 22Rv1 cell lines, including AR‐regulated proteins prostate‐specific antigen (PSA) and human kallikrein 2 (hK2), and the AR‐V7 variant in 22Rv1 cells (Fig. 2A).