RB1 and squamous cell carcinoma: performed NGS in pulmonary LCNEC and found altered TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%) and segregated LCNEC into two main different molecular subtypes: SCLC-like with TP53/RB1 inactivation and MYCL amplification; NSCLC-like with retained TP53/RB1 functions, NOTCH mutations and also with STK11/KRAS/TTF1 mutations, similar to that of adenocarcinoma, or KEAP1 mutations or SOX2/FGFR1 amplification, as with squamous cell carcinoma.