GAPDH and pulmonary fibrosis: CAT is a major antioxidant enzyme in the vascular wall, which is also commonly used as a biomarker of free radical production in studies of AS.[72] CAT can prevent oxidative damage cooperatively at different sites during ROS metabolic pathway activation.[72] Moreover, CAT has been shown to play a protective role in pulmonary fibrosis by protecting lung epithelial cells from hydrogen peroxide–induced apoptosis, thereby reducing susceptibility to COVID-19.[73,74] As a classical glycolytic enzyme, GAPDH is involved in cytosolic energy production.