Tumor-associated macrophages (TAM) derive mostly from circulating monocytes which are attracted into tumor sites, by locally produced chemotactic factors, such as CCL2, CCL5, CCL7, CCL8, CXCL12, vascular endothelial growth factor (VEGF), and macrophage colony stimulating factor (M-CSF) [3]. The gene discussed is CCL2; the disease is neoplasm.