VDR and vitamin D deficiency: It is reported that the skin, brain, gonads, colon, beta−islet cells, prostate, heart, skeletal muscle, monocytes, activated T and B lymphocytes and adipocytes all express the same VDR.(31, 32) Recent studies on VDR in knockout mice revealed that the effects of vitamin D on skeletal health depend exclusively on intestinal Ca absorption.(33) Therefore, the assumption that in various tissues the effect of vitamin D deficiency below the level affecting Ca homeostasis is mediated through VDR, is controversial.