MMP9 and neoplasm: M2 TAMs produce arginase 1 (ARG1), IL-10, transforming growth factor-beta (TGF-β), vascular endothelial growth factor (VEGF), matrix metallopeptidase 9 (MMP9) and prostaglandin E2 (PGE2), thus subverting anti-tumor adaptive immunity and promoting tumor development and spreading [77].