MMP9 increases rapidly after cerebral ischemia and hypoxia, destroying the integrity of the vascular wall by degrading tight junctions and the extracellular matrix to increase the BBB permeability, and further leading to neuronal death, cerebral edema, and hemorrhagic transformation (Yang and Rosenberg, 2011; Shi et al., 2016; Bernardo-Castro et al., 2020). The gene discussed is MMP9; the disease is Cerebral ischemia.