Furthermore, the mechanism by which NBO suppresses MMP-9 and attenuates BBB damage appears to involve the aforementioned inhibition of NADPH oxidase, as the inhibition of NADPH oxidase by apocynin or gp91phox knockout resulted in much lower amplitudes in MMP-9 induction and BBB leakage in ischemia [106]. This evidence concerns the gene MMP9 and ischemia.