HMOX1 and pulmonary arterial hypertension: Since PAH is improved by HO-1 induction [33, 34], PETN is a potential candidate drug for treatment of this severe disease, currently investigated within the CAESAR clinical trial (“ClinicAl Efficacy Study of Pentalong® for PulmonAry Hypertension in HeaRt Failure”; EudraCT Number: 2009-015059-26).