CCL2 and cancer: CCL2, secreted by cancer cells or CAFs, recruits monocytes, MDSCs, and Treg into TME, and these monocytes and some MDSCs are converted into TAMs, which, together with CAFs, induce angiogenesis, ECM remodeling, and EMT of cancer cells; TAMs, MDSCs, and Treg suppress cytotoxic T cells and reduce anti-tumor immunity.