ASCL1 and small cell lung carcinoma: ASCL1 is a master regulator of NE differentiation and a marker for SCLC; however, recent work defined different SCLC molecular subtypes based on the expression of lineage-determining transcriptions factors and demonstrated that subsets of SCLC do not express ASCL1 and are instead driven by other key transcription factors, such as NEUROD1 or POU2F3 [76].