Activation of endogenous ACE2 has hypothesized to change the balance of the RAS from the vasoconstrictive, proliferative axis (ACE-ANG II-AT1R) to the vasoprotective axis [ACE 2-ANG-(1–7)-Mas], resulting in the prevention of pulmonary hypertension (PH). Here, ACE is linked to pulmonary arterial hypertension.