Chemokines secreted by tumor cells or TAMs such as C-C motif chemokine ligand 1(CCL1), CCL2, CCL5, transforming growth factor-β (TGF-β), platelet-derived growth factor, vascular endothelial growth factor (VEGF), and colony-stimulating factor-1 (CSF-1) can recruit monocytes into TME and promote their differentiation into TAMs (10, 11). The gene discussed is CCL2; the disease is neoplasm.