PTGS2 and pulmonary arterial hypertension: Moreover, in severe PAH, decreased expression levels of the PPARγ gene and protein lead to abnormal growth of endothelial and vascular SMCs [81–83]; 2-ME2 promotes the activation of PPAR-related genes in human PASMCs by upregulating cyclooxygenase-2 (COX-2) expression, thereby mitigating abnormal growth [84].