POU2F3 and small cell lung carcinoma: Currently, SCLC is divided into four subtypes: the ASCL1-high (SCLC-A), NEUROD1-high (SCLC-N), POU2F3-high (SCLC-P) and YAP1-high (SCLC-Y) subtypes, which are enriched in WT RB1 [15].