STAT3 and pulmonary arterial hypertension: STAT3 activation was associated with overexpression of Drp1 in both PAECs isolated from PAH rat lung and apoptosis resistant PAECs induced by hypoxia treatment, while AG490 prevented the phosphorylation of STAT3 at tyr705 in hypoxia-induced apoptosis resistant PAECs, and those were associated with the decreased expression of Drp1 protein.