Tumor-infiltrating neutrophils secrete proteases such as metalloproteinase 9 (MMP-9), which is responsible for extracellular matrix degradation and activation of vascular endothelial growth factor (VEGF), which promotes epithelial-to-mesenchymal transition (EMT), intravasation, and angiogenesis—all of which stimulate tumor formation and metastasis (26). The gene discussed is MMP9; the disease is neoplasm.