7,8-Epoxy-vitamin D3 is derived from Vitamin D3 (V676045), which is the vitamin that mediates intestinal calcium absorbtion, bone calcium metabolism and probably, muscle activity. It occurs in and is isolated from fish liver oils. Vitamin D acts through a receptor that is a member of the ligand-dependent transcription factor superfamily. It modulates the proliferation and differentiation of both normal and cancer cells. It also has antiproliferative and antimetastatic effects on breast, colon, and prostate cancer cells. Activated vitamin D receptors in intestine and bone maintain calcium absorbance and homeostasis.