Specifically, polymorphonuclear MDSCs (PMN‐MDSCs), defined as CD45+ CD11b+ F4/80− GR‐1+ Ly6G+, dominated the MDSC population in WT and C1 KO CRC tissues; while, their percentages were significantly reduced in C2–4 KO CRC tissues (Figure S8C,D, Supporting Information). This evidence concerns the gene PTPRC and colorectal carcinoma.