Immunoblot analysis revealed that the five lineage-specific TFs (ASCL1, NEUROD1, YAP1, POU2F3, and ATOH1) are more obviously expressed in a mutually exclusive manner in human SCLC cell lines than in clinical SCLC specimens, with NCI-H211 (H211) cells as an exception, showing clear co-expression of NEUROD1 and POU2F3 (Fig. 2a). This evidence concerns the gene POU2F3 and small cell lung carcinoma.