AR and Familial prostate cancer: A number of RhoGEFs are overexpressed in prostate cancer, including Rac1 GEF P-Rex [14] and Vav3 GEF for RhoA, Rac and CDC42 [15, 16], and are responsible for promoting metastasis and castration resistant prostate cancer (CRPC) by regulating androgen receptor (AR) activity.