Our previous study showed the pathophysiological significance of Cat S activity in pulmonary vascular remodeling due to the disruption of peroxisome proliferator-activated receptor-gamma (PPARγ) in the lungs of IPAH patients and in pulmonary arterial smooth muscle cells (PASMCs) of the rat MCT-induced PAH model [22]. Here, CAT is linked to idiopathic pulmonary arterial hypertension.