JTB, also known as the prostate androgen-regulated (PAR) gene, was previously identified as a target of the androgen receptor (AR) signaling pathway, based on physiological and functional evidence such as dihydrotestosterone-induced expression changes in androgen-sensitive human prostate adenocarcinoma cells (LNCaP) and the restoration of androgen responsiveness following AR reintroduction in the human androgen-independent prostate cancer cell line (PC3) [13]. The gene discussed is AR; the disease is prostate cancer.