CDKN2A and cancer: Considering that p14ARF is a tumor suppressor it is not surprising that most human cancers (colorectal, gastric, prostate, breast bladder, oral, hepatocellular, lung, leukaemia, glioblastoma, and melanoma) are characterized by its inactivation mainly due to its promoter hypermethylation, homozygous deletions and mutations (reviewed in [1]) or just reduced levels whose cause has not been elucidated yet [9].