Mitogen-activated protein kinase activity has been shown to be elevated in CRPC (Abreu-Martin et al, 1999; Gioeli et al, 1999), in which activated MAPK is believed to be able to stimulate prostate cancer cell growth independently of AR by activating various transcription factors including AP-1 (a homo- or heterodimer of phosphorylated c-jun and c-fos) and c-myc (Weinstein-Oppenheimer et al, 2000). Here, AR is linked to prostate cancer.