MMP9 and brain infarction: Oxidative stress induces nuclear translocation of MMP-2 and MMP-9.14 Nuclear MMP-2- or MMP-9-mediated degradation of PARP-1 and XRCC1 results in neuronal accumulation of oxidative DNA in early stages of ischemia.46 These proteins are important in base excision repair pathways for DNA repair, cell survival and apoptosis.14 As a result, injection of MMP inhibitors represses apoptosis in brain infarction.46