CCL2 and neoplasm: All three types of immune cells have two subgroups: pro-tumor and anti-tumor, which are recruited through chemokine/chemokine ligands, colony-stimulating factor-1 (CSF-l)/CSF-1R, VEGF/VEGFR, and cytokines in tumor niche, such as TGF-β1, IL-6, TNF-α, MCP-1 (also known as CCL2), which are also upregulated in obese patient [139,140,141,142,143].