CCR5 and neoplasm: While most of our data are on neutrophils and PMN-MDSCs, since these are the most abundant populations found in most human and mouse tumors,38 39 including the models evaluated, we also observed a polarization of macrophages toward an M1-like phenotype in the tumors of mice treated with shRNAs specific for CCR1 and CCR5, and a loss of suppressive activity of Ly6C+mMDSC differentiated in vitro by tumor derived factors in the presence of CCR1 and CCR5 inhibitors.