3-(4-Maleimidoacetamido)propyl-25-Hydroxy-Vitamin D3 is a derivative of Vitamin D3, 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.