CTLA4 and small cell lung carcinoma: In the present study, we ascertained the differential expression of ASCL1, NEUROD1, POU2F3, YAP1 on a large number of surgically resected SCLC tumors both on RNA and protein levels and then performed an evaluation of the prognostic value between dominant subtype markers, followed by an examination on differential expression in several cell surface proteins, including CD8, FoxP3, PDL1, CTLA4, etc.