CCL2 and neoplasm: Major sources of TAMs are resident tissue macrophages as well as monocyte-derived macrophages, intensively recruited into the growing tumor by chemotactic factors, like CCL2 (4, 7, 8) The are two major vectors of macrophage polarization: M1-type, classically activated, pro-inflammatory, and M2-type, alternatively activated, generally considered as anti-inflammatory or tolerogenic macrophages (4–6).