IDO1 and neoplasm: Notably, activation of IFN signaling in response to agonistic CD40 mAb treatment was also associated with expression of genes previously suggested to be part of a tumor endothelial barrier that limits T-cell infiltration, activation and viability, including IDO1 and TNFSF10 (TRAIL) (Supplementary Table S3).24 To validate our results, we performed quantitative PCR (qPCR) analysis of gene expression for selected DE candidate genes in the original samples used for RNA-sequencing from the B16.F10 tumors.