HMOX1 and idiopathic pulmonary fibrosis: Antioxidant enzyme defense systems (including SOD, CAT, GPx, reduced glutathione and heme oxygenase 1) are directly regulated by Nrf2, which becomes a potential therapeutic target in lung diseases such as Idiopathic Pulmonary Fibrosis, asthma, COPD and acute respiratory distress syndrome [237,238].