CDKN2A and neoplasm: MTAP deletion leads to an immunosuppressive TME, with some reports indicating that MTAP knockout (KO) results in the upregulation of PD-L1 in tumor cells,8 while others have found significantly reduced PD-L1 staining in tumors with 9p21.3 loss (without distinguishing between CDKN2A and MTAP).7