In addition to creating an anti-inflammatory environment, these cells also produce factors that can directly promote tumor growth and vascularization such as matrix metallopeptidase 9 and TGFβ while cytokines produced by the tumor cells (e.g., GM-CSF, IL-6, and VEGF) limit differentiation of myeloid cells and promote MDSC development (41). Here, MMP9 is linked to neoplasm.