CD4 and neoplasm: Tumor related chemokines, such as C-C motif chemokine ligand (CCL)4, CCL5, and CCL20, and C-X-C motif chemokine ligand 10 (CXCL10) can act as chemoattractants for immune cells, including CD8+ T cells, CD4+ T helper type 1 lymphocytes, CD4+ regulatory T cells, and natural killer cells [29, 30].