CCL2 and neoplasm: The CCL2/CCR2 axis is the main pathway implicated in monocytes/M-MDSCs migration,50 while neutrophils/PMN-MDSCs are recruited mainly by the CXCLs-CXCR1/2 axis.51 Moreover, it was found that the expression of chemokine CCL26 in tumor cells induced the accumulation of CX3CR1+ MDSCs,52 and the CCR5/CCR5 ligand axis also supported the maintenance of MDSCs in the tumor niches.53