STAT3 and idiopathic pulmonary arterial hypertension: Moreover, STAT3 has been shown to be phosphorylated in endothelial cells from lesions of idiopathic pulmonary arterial hypertension, suggesting that activation of STAT3 contributes to the proliferative pulmonary vascular lesions in IPAH lungs [90], and it is known that ROS can activate STAT3, so it is likely that phosphorylated processes are involved in the ROS-mediated hyperproliferation of HPAECs.