In HCC tumor microenvironment, several cytokines and chemokines such as CXCL1, CSF1, CCL2, CCL9, IL-6, and IL-18 etc., which were secreted from either HCC cells or immune cells, promotes the recruitment and infiltration of MDSCs from the bone marrow into HCC tumor site 32-34. The gene discussed is CCL2; the disease is hepatocellular carcinoma.