MMP9 and neoplasm: Similar to TAMs, products secreted from neutrophils, including reactive oxygen species, cytokine (IL-8), growth factors (VEGF and HGF), and proteinases [arginase (ARG 1), MMP-2, MMP-8, MMP-9, and MMP-13], have defined and specific roles in both regulating tumor cell proliferation, angiogenesis, and metastasis and suppressing the anti-tumor immune response (64).