CCL2 and cancer: In particular, the chemokines CCL2, CCL3, CCL4, CXCL9 and CXCL10 are known to be potent chemoattractants for tumor-infiltrating T cells [48] and increased expression of these chemokines has been shown to be associated with infiltration of tumor-specific T cells in cancer patients and various mice models of cancer [47–54].