Mitochondrial gate-keeper enzyme pyruvate dehydrogenase subunit E1 alpha (PDHA1) also presented higher expression of mRNA levels in PAH-EC than control cells and CTEPH-EC (Fig. 2B), while mRNA levels of PDK1 were not found differently expressed between all three groups (Fig. 2B). This evidence concerns the gene PDK1 and pulmonary arterial hypertension.