CXCL9 and cancer: Indeed, a study correlating chemokine expression and CD8+ T cell infiltration in human solid tumors showed that chemokine C–C motif ligand (CCL) 5 and CXCL9 had the highest correlation with CD8+ T cell infiltration across different cancer types and also demonstrated cooperation between CXCL9/10 and CCL5 in recruiting effector T cells into tumors [31].