EDN1 and pulmonary arterial hypertension: Specifically, we sought to establish (1) the effect of statins on PASMC proliferation, apoptosis and production of factors (endothelin-1 and matrix metalloproteinase-9) implicated in the pathogenesis of PAH; (2) the anti-proliferative effect of statins when used in combination with established therapies for PAH and (3) the intermediates in the mevalonate pathway responsible for the action of statins.