Traditional SCLC is currently subdivided into four molecular subtypes on the basis of transcription factor expression: ASCL1 (SCLC-A), NEUROD1 (SCLC-N), POU2F3 (SCLC-P), and YAP1 (SCLC-Y) [161, 162]. Here, POU2F3 is linked to small cell lung carcinoma.