Interestingly, X-ray irradiation has been shown to induce demethylation of the whole genome by inhibiting DNA methyltransferases (DNMTs) [20–25], which raise the possibility that X-ray irradiation might inhibit lung cancer cell proliferation and invasion via demethylation-mediated up-regulation of the Dab2 gene. This evidence concerns the gene DAB2 and lung carcinoma.