MMP9 and Stroke: Accumulating evidence suggests that ABCB1 transporters as well as MMP-9 activity are regulated by the nuclear factor-kappa B (NF-κB) signaling pathway under non-stroke conditions (Nakanishi and Toi, 2005; Katayama et al., 2014; Chiu et al., 2015; Andersson et al., 2018).