These include the CCR5 ligands, CCL3, CCL4 and CCL5, and the CXCR3 ligands, CXCL9, CXCL10 and CXCL11.52, 53 Although CCR5 expression is crucial for both the recruitment and effector functions of CD8+ T-cells in solid tumours,53 there is also a non-redundant role for CXCR3 in controlling CD8+ T-cell trafficking to human and murine melanoma, not achievable by CCR5.52 This could potentially explain why the overexpression of CCL5 in many tumour models is more often associated with pro- and not anti-tumorigenic outcomes, because of its ability to also promote monocyte infiltration.54 This evidence concerns the gene CCR5 and melanoma.