Some studies showed an increased MMP-2 activity in lung tissue in patients with idiopathic PAH (IPAH); increased levels of proMMP-2 in the urine of patients with associated PAH; higher plasma concentrations of MMP-2 in PH patients with SVR < 1440 dyn·s·cm−5; activation of MMP-2 in patients with plexogenic pulmonary arteriopathy. This evidence concerns the gene MMP2 and pulmonary arterial hypertension.