To provide insights into whether ERRα would play a role in the castration-relapse growth in prostate cancer, we next examined the expression patterns of ERRα and also several major steroidogenic enzymes in an established castration-relapse xenograft tumor model VCaP-CRPC, in which AR-axis signaling was reactivated in castration-relapse VCaP xenograft tumors as compared to that in pre-castration 18, 27. This evidence concerns the gene AR and Familial prostate cancer.