The chemokine receptor and ligand crosstalk between TAMs and tumor cells, such as C-C motif chemokine receptor 2 (CCR2)/C-C motif chemokine ligand 2 (CCL2), CCR5/CCL5, C-X-C motif chemokine 1(CXCR1)/CXCR2/CXCL8 (also known as IL-8), CCR4/CXCL12 (also known as SDF-1), CCR6/CCL20 (also known as MIP-3α), plays a crucial role in recruiting monocytes to infiltrate tumors, promoting macrophage polarization toward the M2-like phenotype and protecting tumor cells from chemotherapy-induced apoptosis [194,195]. The gene discussed is CCR4; the disease is neoplasm.