The current study therefore measured the effects of combining vitamin D3 with 5-FU on colon cancer regression and the expression of Wnt/β-catenin, TGF-β1 and its related molecules, HSP-90, iNOS and COX-2 in an intermediate (15 weeks) AOM experimental model in rat. The gene discussed is NOS2; the disease is malignant colon neoplasm.