This interesting and unexpected finding demonstrated: 1) in hypoxic PAH, the gene and protein levels of CF6 in lung tissue were significantly lower; 2) no significant change in CF6 levels was observed in blood samples from the tail vein or lung vasculature in hypoxia-induced PAH; and 3) the local mitochondrial ATP synthase activity in the lung tissue showed a significant decrease only after four weeks of hypoxia. The gene discussed is ATP5PF; the disease is pulmonary arterial hypertension.