It is therefore possible that tumor-infiltrating myeloid cells play dual roles in CRC: 1) these cells respond to commensal bacteria and promote tumor-associated inflammation (such as the production of IL-23 and IL-17), which subsequently leads to reduced CXCL9/10 production and T cell attraction; 2) these cells may serve as suppressors of anti-tumor immunity. This evidence concerns the gene CXCL9 and colorectal carcinoma.