CDKN2A and neoplasm: Allele loss in 3p21.3 and 9p21 impair several TSGs such as RASSF1A and CDKN2A. The homozygous deletion of CDKN2A (p16) and CDKN2B (p15) located in the 9p21.3 region was observed in primary NPC tumours [31].