NOX4 and pulmonary hypertension: In contrast, Veith et al. [60] determined that mice deficient in Nox4 exposed to acute (1% O2 for 180 min) and chronic normobaric hypoxia (10% O2 for 21 days) did not display differences in their responses to pulmonary hypertension induced by either model of hypoxia, demonstrating that the generation of ROS from Nox4 does not play a role in the development of HPV or pulmonary hypertension.