ASCL1 and small cell lung carcinoma: Rudin et al. identified four molecular subtypes of SCLC, including ASCL1, YAP1, NEU-ROD1, and POU2F3, based on the level of expression of the following transcription factors: achaete-scute homolog1, yes-associated protein 1, neurogenic differentiation factor 1, and POU class2 homeobox 3, respectively.