In NSCLC xenografts metformin given orally (in drinking water) at a dose of 250mg/kg/day enhanced the activation of ATM - AMPK - p53/p21cip1 axis induced by RT, inhibited tumor growth and enhanced the cytotoxicity of RT, inhibited angiogenesis and enhanced the induction of apoptotic markers. Here, ATM is linked to non-small cell lung carcinoma.