SCLC is categorized into four major subtypes by relative gene expression of four key transcription regulators defining subtypes: SCLC-A (ASCL1), SCLC-N (NeuroD1), SCLC-P (POU2F3) and SCLC-Y (YAP1) (8). This evidence concerns the gene POU2F3 and small cell lung carcinoma.