A previous study in bovine-derived PASMCs observed serotonin-stimulated production of ROS serving as an intermediate in the transactivation of PDGFR-β by serotonin, where oxidation of PTPs was suggested as the mechanism involving SERT rather than the 5-HT receptors.45 In line, we observed that in female human PASMCs, PDGFR-β expression is increased in PAH-hPASMCs versus control hPASMCs. This evidence concerns the gene SLC6A4 and pulmonary arterial hypertension.