INSM1 and small cell lung carcinoma: The SCLC-A is defined by high expression of the neuroendocrine transcription factor achaete-scute homolog 1 (ASCL1), with concomitant upregulation of MYCL, BCL2, SOX2, and DLL3 (delta-like ligand 3).SCLC-N, marked by NEUROD1-driven neuroendocrine differentiation, co-expresses oncogenic MYC with neural development factors INSM1 and HES6. SCLC-P is governed by the lineage-specific factor POU2F3, whereas SCLC-Y demonstrates YAP1-mediated Hippo pathway dysregulation.