CCL2 and neoplasm: In the tumor microenvironment, increased C–C motif chemokine ligand 2 [CCL2, also known as monocyte chemoattractant protein-1 (MCP-1)] and IL-6 induce the recruitment of myeloid-derived suppressor cells (MDSCs), which are known to be immune-suppressive cells that inhibit antitumor immunity24.