Neutrophils could release MMP-9 [14], Bv8 [15], Arginase-1 (Arg-1) [16], and inducible nitric oxide synthase (iNOS) [17], which not only promote tumor angiogenesis [14, 15, 17], but also suppress the proliferation and cytotoxicity of CD8+ T cells [16], thus suppressing the anti-tumor immune response and promoting tumor growth and metastasis. Here, MMP9 is linked to neoplasm.