The current study also measured the possible synergistic interactions between vitamin D3 and 5-FU in the regulation of cell proliferation, differentiation and angiogenesis in colon cancer at the molecular level by measuring the expression patterns of Wnt/β-catenin pathway, TGF-β and its related molecules, HSP-90, COX-2 and iNOS at the protein and gene levels. The gene discussed is HSP90AA1; the disease is colonic neoplasm.