TP53 and cancer: In a study of the cancer genome atlas (TCGA), GC was categorized into 4 subtypes, including Epstein-Barr virus subtype, microsatellite instability (MSI) subtype, genome-stable (GS) subtype, and chromosomal instability (CIN) subtype.[12] It was identified that GCA is a CIN subtype cancer similar to the Lauren intestinal-type, which is enriched in TP53 mutations and receptor tyrosine-kinase-RAS activation.[13] The metabolism of nicotinamide mediated by NNMT was found to be associated with tumor initiation and inflammation-induced angiogenesis.