TMPRSS2 and prostate cancer: Indeed, many androgen-regulated genes have been identified and shown to be important in prostate cancer, including PSA (prostate specific antigen) [9], hKLK2 (human kallikrein-2) [10], TMPRSS2 (transmembrane protease, serine 2) [11], ETV1 (Ets variant gene 1) [12], and sGCα1 (soluble guanylyl cyclase α1) [13].