NOX4 and pulmonary arterial hypertension: Only modest protective effects on RVSP were evident in hypoxic PH Nox4−/− mice; this is in alignment with a previous study using a small-molecule Nox4 inhibitor, showing some effects on RVH and vascular remodeling.45 As such, the important role for Nox1 in mediating PAH phenotypes that were observed in vitro were paralleled in vivo where Nox1−/− mice were protected from hypoxia-induced vascular injury.