PSMC4 and pulmonary arterial hypertension: Our study found 6 upregulated mitochondrial genes (Psmd2, Psmc4, Psmc3, Psmc5, Psmd13, and Psmc2) and 3 downregulated mitochondrial genes (Lipe, Cat, and Prkce) which are significantly differentially expressed in the lung tissue of PAH rats.