MMP9 and brain ischemia: However, a single dose of LGU (0.24, 2.16 mg/kg) in the tail vein can up-regulate the expression of tight junction proteins ZO-1 and occludin and inhibit the expression of MMP-9 after cerebral ischemia/reperfusion, suggesting that LGU may up-regulate tight junction proteins ZO-1 and occludin.