MMP9 and glioma: GBM recruits and reprograms infiltrating neutrophils through chemokine-driven trafficking, hypoxia, and tumor-derived cytokines, promoting angiogenesis, glioma stem-like cell support, and immune suppression via vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 release (MMP-9), arginase-1, and neutrophil extracellular traps (NETs).