MMP2 and triple-A syndrome: Kurogi et al. (2015) discovered that up-regulation of TIMP-1 expression in the early stage of cerebral vasospasm may contribute to the recovery of ECM in the later stage of cerebral vasospasm. MMPs are key proteases in ECM degradation. MMPs could promote the development of AAA by degrading elastic and collagen fibers in aortic tissues, especially MMP-2 and MMP-9, which were considered as critical regulators in AAA progression (Li et al., 2020b). In hypoxic endothelial cells treated with tissue plasminogen activator, the release of MMP-2 contributes to ECM degradation (Song et al., 2016).