C-C motif chemokine ligand-2 (CCL2), through its receptor CCR2 (which is expressed on the surface of M2 TAMs), upregulates PD-L2 expression in M2 TAMs and reduces CD8 cytotoxic T lymphocyte (CTL)-mediated apoptosis of esophageal cancer cells (ESCCs), thereby causing immune escape in ESCC [+73]. Here, CCL2 is linked to esophageal squamous cell carcinoma.