In addition, MDSCs induce Treg differentiation through TGF-β-dependent and -independent mechanisms involving CD40 or IL-10 and IFN-γ, respectively (100, 106), induce NK cell anergy through membrane-bound TGF-β1 (107, 108), promote tumor angiogenesis by MMP-9 secretion or direct differentiation into EC (109), and stimulate tumor growth through the release of cytokines and growth factors (101). This evidence concerns the gene MMP9 and neoplasm.