NOX4 and pemphigus foliaceus: In the present study, we found that FA inhibited the expression level of the inflammatory factor IL‐6, and the expression of apoptosis‐related genes FasL, Fas, Bax/Bcl‐2, Cleaved caspase‐3, Cleaved caspase‐3/caspase‐3, suppressed the expression of oxidative stress‐related gene NOX4 in the lung tissues of mice with BLM‐induced PF, elevated the expression of antioxidant‐related genes HO‐1, CAT‐1, and p‐Nrf2/Nrf2 expression, and improved the pathological changes in lung tissues, suggesting that the improvement of PF by FA is related to the regulation of apoptosis and oxidative stress.