ASCL1 and small cell lung carcinoma: On the basis of the expression phenotypes of the four markers, we divided these samples into four molecular subtypes: SCLC-A subtype (ASCL1-high), SCLC-N subtype (NEUROD1-high), SCLC-Y subtype (YAP1-high), and SCLC-P subtype (POU2F3-high).