VDR and cancer: Apart from its function in calcium and phosphate homeostasis, vitamin D is known to exert strong anti-proliferative, pro-differentiation and pro-apoptotic actions in numerous cell types and tissues, including cancers.14 The biologically active metabolite of vitamin D, 1,25-dihydroxy-vitamin D [1,25(OH)2D], acts through binding to the vitamin D receptor (VDR), a member of the nuclear steroid hormone receptor superfamily.