However, the relative activities of the FKBP51-bound and FKBP52-bound androgen receptors differ from that observed for the glucocorticoid and progesterone receptors such that a positive-feedback expression process can arise under pathological conditions which appears to often substantially contribute to the metastatic phase of prostate cancer [10–12]. This evidence concerns the gene FKBP4 and prostate carcinoma.