In vivo, lipopolysaccharide (LPS) induces CXCR2+ and polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) accumulation through the production of TLR4-dependent CXCL1, controls CCA tumor cells to form an immunosuppressive microenvironment, and facilitates CCA tumor growth 104. The gene discussed is CXCL1; the disease is cholangiocarcinoma.