IDO1 and breast cancer: Using cBioPortal, it was found that PRKDC (DNA‐PK encoding gene) tended to coexist with the functional markers of MDSCs which include NOS2 (iNOS‐encoding gene), Arg1 (Arg1‐encoding gene), and IDO1 (IDO‐encoding gene) in 19 breast cancer studies involving 9134 patients/9555 samples.