POU2F3 and small cell lung carcinoma: Rudin et al. describe four subtypes of SCLC based on expression of transcription regulators including SCLC-A, defined as ASCL1-high, SCLC-N, defined as NEUROD1-high, SCLC-Y defined as YAP1 high, and SCLC-P defined as POU2F3 high (Schwendenwein et al., 2021).