TP53 and neoplasm: Genome studies have identified frequent somatic molecular alterations in SCLC cells including functional inactivation of TP53, RB1, and, less commonly, PTEN tumor suppressor genes; copy number amplification of MYC family genes MYC, MYCL1, and MYCN; mutations in the EP300, CREBBP, and KMT2A (MLL) and KMT2D (MLL2) genes encoding histone-modifying proteins; inactivating mutations in NOTCH family genes; and common loss of genomic regions containing FHIT and CDKN2A genes [2, 5–8].