Recently, using a mouse model of melanoma, Schlecker et al. [13] demonstrated that tumor-infiltrating monocyte-MDSCs directly attract high numbers of T-regs via CCR5 and that intratumoral injection of CCL4 or CCL5 increases tumor-infiltrating T-regs, but CCR5 deficiency led to their profound decrease. This evidence concerns the gene CCL5 and melanoma.