CCL2 and neoplasm: M1 TAMs secrete pro-inflammatory cytokines, such as IL-12, IL-23 and TNF-α, MMP-9 and increased levels of interferon-(INF-γ)-inducible chemokines (CCL2, CCL5, CXCL9, CXCL10 and CXCL16), which induce PD-L1 expression on macrophages and participate in the anti-tumour immune response by contributing to the Th1 activity, by inhibiting proliferation and by exerting cytotoxic ability.