In addition, p16 (MTS, multiple tumor suppressor 1), DAPK (death-associated protein kinase), MGMT (O6-methylguanine-DNA methyltransferase), PI3K (the phosphatidylinositol 3-kinase), c-myc and other genes were investigated in oral tobacco-related tumor tissues and cancer associated adjacent tissues21,29-32. This evidence concerns the gene CDKN2A and cancer.