ASCL1 and small cell lung carcinoma: Recently, transcriptomic profiling on tumor samples of SCLC has defined 4 different subtypes, characterized by positivity to ASCL1 (A), NEUROD1 (N), POU2F3 (P) transcription factor signatures or by the lack or low expression of these three signatures and associated with an inflammatory gene expression signature (SCLC-I) [18].