POU2F3 and small cell lung carcinoma: In recent years, the consensus definition of SCLC subtypes has transitioned from classical/variant classification to neuroendocrine (NE)/non-neuroendocrine (non-NE) classification, with further subgroup categorization based on specific transcription factors, i.e., NE transcription factors ASCL1 and/or NEUROD1 (43, 44), non-NE variants associated with POU2F3, and a hypothetical fourth subtype driven by the transcription factor YAP1 (45).