Metformin inhibits cancer cell proliferation and we have shown that it has radio-sensitizing properties in lung cancer in-vitro[6] These notions suggest a need to understand in depth the effects of IR on the expression and activity of the Akt-mTOR and AMPK signaling pathways in tumours in order to understand better tumour radiation biology and assist in a rational development of new effective radio-sensitizers. The gene discussed is MTOR; the disease is cancer.