To determine whether SOX17 is regulated by factors implicated in the development of PAH, we tested SOX17 expression in endothelial colony-forming cells (ECFC) derived from healthy controls or PAH patients after stimulation with the hypoxia mimic DMOG (dimethyloxalylglycine), the inflammatory stimulus LPS (lipopolysaccharide) and the BMPR2 ligand BMP9 (bone morphogenetic protein-9). The gene discussed is SOX17; the disease is pulmonary arterial hypertension.