In this study, we found that ROS, presumably produced through NADPH oxidase, gradually accumulated after brazilin treatment in RA FLS, and blocking of the ROS production with antioxidant NAC completely blocked the brazilin-induced autophagy (Fig 4), suggest that brazilin-induced ROS production is essential for the induction of autophagy. The gene discussed is FMO5; the disease is rheumatoid arthritis.