NOX4 and chronic obstructive pulmonary disease: Yuan et al. found that NOX4/ROS and CSE/H(2)S signaling pathways may play an important role in the pathogenesis of chronic obstructive pulmonary disease- (COPD-) related pulmonary hypertension (PH) by detecting the expression of NOX4 and CSE proteins in lung tissue by immunohistochemistry and measuring the thickness of pulmonary arteriole walls [4].