Fig. 11 summarizes FKBP51 interactions and signal transduction pathways examined in this article. Preclinical studies have shown that treatment with drugs that target FKBP5 exerts antitumor effects on glioblastoma mouse models [79,92]. A caveat is, however, envisaged. FKBP51, whether on the one hand is aberrantly expressed by the tumor cells, on the other hand, is constitutively expressed in immune cells with a role in immune activation and proliferation [40]. This evidence concerns the gene FKBP4 and neoplasm.