In contrast to other macrophages, TAMs have specific receptors and ligands; for example, TAM can enhance phagocytosis by binding to extracellular matrix metalloproteinase ligands (e.g., MMP-2, MMP-7, MMP-9, and MMP-12), which in turn promotes tumor growth and metastasis34,35. This evidence concerns the gene MMP12 and neoplasm.