CCL22 and neoplasm: The tumor expresses various chemokine ligands such as chemokine (C-C) ligand 17 (CCL17) and chemokine (C–C) ligand 22 (CCL22), which facilitate recruitment of CC Chemokine Receptor 4 (CCR4+) regulatory T-cells (Tregs), while C-X-C motif chemokine receptor 3 (CXCR3)-with its ligands, C-X-C motif chemokine ligand 9 (CXCL9) and C-X-C motif chemokine ligand 10 (CXCL10)—promotes trafficking of cytotoxic lymphocytes into the GBM tumor site.