Some reports show that, although chemokines such as C-C chemokine ligand 2 (CCL2) which belongs to the C-C chemokine family, are highly secreted by solid tumors, the corresponding chemokine receptors (CCR), such as CCR2b and CCR4, that can specifically bind CCL2 are minimally expressed on T cells, resulting in a lack of homing to the tumor site [57]. Here, CCL2 is linked to neoplasm.