Thus, all these data indicate that the induction of the global DNA hypomethylation via the disruption of the DNMT1/PCNA interactions is a process associated with the acquisition by astroctyes, mammalian epithelial cells, lung fibroblast and mesothelial cells of three phenotypes of cancer: high proliferation rate, resistance to cell death and tumorigenic capacity. This evidence concerns the gene DNMT1 and cancer.