NEUROD1 and small cell lung carcinoma: Recent studies have reported that the subtypes of small cell lung cancer contained atonal bHLH transcription factor 1 (ATOH1), pOU class 2 homeobox 3 (POU2F3), neurogenic differentiation factor 1 (NEUROD1), and achaete–scute complex homolog-like (ASCL1) [114,115].