GPX4 and pulmonary arterial hypertension: Ferroptosis is upregulated in the pulmonary arterial endothelial cells (PAECs) of the MCT-induced PAH rat models, and is characterized by lipid peroxidation, increased cellular iron levels, mitochondrial damage, abnormal expression of GPX4, ferritin heavy chain 1 (FTH1), and NADPAH oxidase 4 (NOX4), activation of inflammatory factors, and severe pulmonary artery remodeling.