Induces proinflammatory cytokines and chemokines, including CXCL8, IL‐1β, and TNF‐α. MMP‐9 damages BBB integrity by degrading TJs and the ECM to promote cerebral edema. Late elevated MMP‐9 levels are associated with poor outcome, whereas reduced MMP‐9 levels on admission are associated with better NIHSS scores. The gene discussed is MMP9; the disease is edema.