RB1 and small cell lung carcinoma: Cell cycle regulators, transcription factors (TFs) and chromatin modifiers including RB1 and TP53, members of MYC family, SOX2, MLL1/2, CREBBP-EP300, RBL2, and TP73 are frequently altered in SCLC, causing aberrant expression of a broad range of genes related to neuronal and neuroendocrine differentiation and proliferation [25–28].