PMEPA1 and Familial prostate cancer: Our recent studies clearly categorize five PMEPA1 isoforms into the following two subgroups: (1) androgen-responsive PMEPA1-b and PMEPA-e, whose expressions were induced by linear dosages of androgen and ectopic AR in androgen responsive prostate cancer cells; and (2) TGF-β-responsive PMEPA1-a, PMEPA1-c, and PMEPA-d which were up-regulated by TGF-β treatment and over-expression of TGF-β receptor I [1,11].