CCL2 and neoplasm: At the biological level, chronically inflamed cells play a major role in the tumor microenvironment, which promotes tumor growth and metastasis by producing cytokines such as TNF-α, CCL2, CXCL8, IL-6 and TGF-β and by inducing infiltration of leukocytes comprising innate immune cells including macrophages, neutrophils, mast cells, dendritic cells, and natural killer cells, as well as adaptive immune T cells and B cells [14, 22].