MMP9 and brain ischemia: There was no significant change in ZO-1 expression (a tight junction protein modulated by MMP-9) between control and cKO mice in response to 2h-ischemia/4h-reperfusion (Fig. 7E), indicating the critical role of MMP-2/occludin pathway in neuronal ZnT3-modulaed BBB disruption in response to cerebral ischemia.