Classical monocytes recruited to tumor site by chemokines, including colony-stimulating factor 1 (CSF-1), chemokine (C-C motif) ligand 2 (CCL2), and chemokine (C-C motif) ligand 5 (CCL5), then polarized into M2 tumor-associated macrophages (TAMs) (39). The gene discussed is CCL2; the disease is neoplasm.