CHEK1 and small cell lung carcinoma: This current work is in direct contrast to previously published work demonstrating that Chk1 inhibition in small cell lung cancer cells increased TBK1 and IRF3 phosphorylation, CCL5, IFN-β and CXCL10 mRNA expression, and elevated PD-L1 expression all indicative of a type I IFN response [45].