MMP9 is upregulated in epilepsy models, and this ECM proteinase has been shown to degrade the specialized ECM called perineuronal nets (PN) surrounding PVINs (Kim et al., 2009; Acar et al., 2015; Rankin-Gee et al., 2015; Dubey et al., 2017). Here, MMP9 is linked to epilepsy.