Nox2 and Nox4 are up-regulated in lung tissues from animal models and humans with PAH (Green et al., 2012; Barman et al., 2014), and they are likely involved in the development of increased pulmonary artery resistance and pressure (Liu et al., 2006; Demarco et al., 2010; Wu et al., 2017a). This evidence concerns the gene CYBB and pulmonary arterial hypertension.