MDSCs along with tumor associated macrophages (TAMs) also play an important role in angiogenesis: secretion of VEGF, platelet-derived growth factor (PDGF), and matrix metalloproteinase-9 (MMP-9) by TAMs and MDSCs leads to increased tumor vasculature, providing nutrients for tumor growth [32,33]. This evidence concerns the gene MMP9 and neoplasm.