In hypoxic WT lungs, an increase in JNK1/2 phosphorylation was associated with PH-like pathology.Hallmarks of PH pathophysiology, i.e. excessive accumulation of extracellular matrix and vessel muscularization with medial wall thickening, was also detected in hypoxic JNK1<sup>-/-</sup> lungs, but not in hypoxia-exposed JNK2<sup>-/-</sup> lungs.