In the MMP family, the upregulation of gelatinases (MMP-2 and MMP-9) was identified in monocrotaline (MCT)–induced or hypoxia-induced mouse model of PH, and gelatinases were considered possible therapeutic targets for the treatment of PAH (George and D'Armiento, 2011; Liu et al., 2018). This evidence concerns the gene MMP9 and pulmonary arterial hypertension.