TP53 and neoplasm: Other than potentiating the chemosensitivity of chemotherapeutic drugs, the addition of metformin (IP, 250 mg/kg, once a day) prior to ionizing radiation (IR) demonstrates a better mitigation of the tumor growth up to 59% inhibition as compared to 4.5% in metformin-treated and IR-treated HCT116 p53−/− xenografts mice [48].