CDKN2A and malignant colon neoplasm: In other tumors, including lung, head and neck, breast, prostate and colon cancer, inactivation of p15 occurs rarely and with concomitant inactivation of p16. It has been shown that aberrant methylation of p15 is associated with transcriptional loss of this gene and treatment with the demethylating agent decitabine leads to reactivation of p15, inducing growth arrest and apoptosis in myeloid cell lines (27).