RB1 and lung adenocarcinoma: At the level of gene mutations, 38 genes were found as recurrently mutated in lung adenocarcinomas and 20 in LSQCCs; only six genes, including TP53, RB1, ARID1A, CDKN2A, PI3KCA and NF1, were recurrently mutated in both types, with TP53, CDKN2A and PIK3CA being more frequently mutated in LSQCCs than in lung adenocarcinomas [43].