Pulmonary inflammation, generated by overexpressing 5-lipoxygenase (a condition observed in hPAH patients), was associated with severe PAH in Bmpr2+/− rats, while neither the single ‘hit’ of Bmpr2 haploinsufficiency nor 5-LO-specific pulmonary inflammation alone initiated the disease—their combined presence was required to develop a lethal PAH [200]. Here, ALOX5 is linked to pulmonary arterial hypertension.