PSMC4 and pulmonary arterial hypertension: To verify the specific expression of critical genes in the lung tissue of PAH rats, we further determined the expression of nine identified essential genes (six upregulated genes Psmd2, Psmc4, Psmc3, Psmc5, Psmd13, and Psmc2; three downregulated genes Lipe, Cat, and Prkce) in the lung tissue between PAH rats and normal rats using qPCR.