The roles of the larger FKBPs are less understood, but FKBP51 and FKBP52 have emerged as likely contributors to health and disease, in particular, for their potential as therapeutic targets for the treatment of a variety of hormone-dependent diseases including stress-related disorders, immune and reproductive functions, and a variety of cancers [4,5,6,7]. The gene discussed is FKBP4; the disease is cancer.