POU2F3 and small cell lung carcinoma: SCLC subtypes were recently characterized and defined by the relative expression of genes encoding four major transcriptional regulators, ASCL1, NEUROD1, POU2F3, and YAP1 (defining subtypes SCLC-A, SCLC-N, SCLC-P, and SCLC-Y, respectively)17.