IDO1 and cancer: In particular, the differentially regulated Ido1 gene caught our attention in the RNA-seq dataset because it encodes for the enzyme indolamin-2,3-dioxygenase, which has immune-suppressive functions in various cancer types including CRC.41–43 As expected from the enrichment plots for IFNγ signaling, Ido1 mRNA expression was downregulated in Tyk2Δ/Δ tumors and upregulated in Tyk2ΔIEC tumors (Figure 2f,g, Supplementary Figure 3c-e).