MMP9 and pulmonary arterial hypertension: This contention is supported by reports of increased gelatinase activity in PASMCs from patients with PAH [29] and pulmonary vessels from rat models of pulmonary hypertension [25], and the finding that MMP-2 and MMP-9 is suppressed, together with vascular remodelling, in animals treated with iloprost and inhibitors of cAMP-PDE activity [43,47].