In colon cancer, metformin monotherapy was more effective than active vitamin D3 (VD3) against cancer, resulting in higher levels of p21, p27, phosphatase and tensin homolog (PTEN), BCL2-associated X protein (BAX), cytochrome C (Cyto-C),and caspase-3(Casp-3). The gene discussed is PTEN; the disease is cancer.