CXCL9 and melanoma: Four of these Top HRLs are recognized by 2 of the Top HRs and represent ligand-receptor pairs that have been previously identified as crucial mediators of T and B cell trafficking in melanoma: CXCL10 and CXCL9 are ligands for CXCR3; and CCL4 and CCL5 are ligands for CCR5 (Fig. 2A).