Schmid et al. (1998) characterized that homozygous deletion of MTAP in primary NSCLC was more frequent than CDKN2A. This observation was further validated in multiple forms of human cancers, which was suggested to confer heavy dependence on the PRMT5 arginine methyltransferase activity in cancer cells (Kryukov et al., 2016). Here, PRMT5 is linked to cancer.