POU2F3 and small cell lung carcinoma: Distinct SCLC subtypes have been defined based on the expression of the transcription factors ASCL1, NEUROD1, POU2F3, and YAP1 [6]; however, a recent study has revealed that instead of a permanent subtype, there is a MYC-driven temporal shift from ASCL1-positive to NEUROD1-positive and then to YAP1-positive states (Fig. 3).