STAT1 and cancer: Ido1-derived metabolites promote immunosuppression and T cell anergy.43 We recently showed in intestinal tumors of ApcMin mice that Ido1 is predominantly expressed by Mmp7+ Paneth-like cancer cells in an IFNγ/Stat1-dependent manner.28 Therefore, we performed immunofluorescence (IF) staining for Mmp7 and Ido1 in Tyk2Δ/Δ and Tyk2ΔIEC tumors (Figure 4a,b).