CDKN2A and neoplasm: The MTAP gene is located on chromosome 9p21 and is frequently found to be co-deleted with CDKN2A and CDKN2B, which encode p16 and p15, respectively.37,38 Given that p16 and p15 are thought to be tumor suppressors and their loss facilitates cell cycle progression,39,40 it is unclear whether the clinical effect of MTAP deletion occurs independently of these events or is an incidental consequence.