NOS3 and pulmonary arterial hypertension: While increased DNA hypermethylation leads to suppression of genes (Sod2 and Nos3) encoding vasodilatory proteins and antioxidants in lungs of hypoxic mice, pulmonary artery SMCs of fawn‐hooded rats, and endothelial cells of fetal lamb with pulmonary hypertension (Archer et al., 2010; Joshi et al., 2020; Ke et al., 2018).