The BMPR2 dysfunction that occurs during PAH leads to decreased PPARγ activity,increased mitogen-activated protein kinase activity and subsequent stimulationof pulmonary vascular remodelling via the platelet-derived growth factor-β(PDGFR-β) pathway.40,83 Given that BMPR2-mediated PPAR-γ activation occurs earlierthan Smad1/5/8 phosphorylation, this appears to be independent of the Smadsignalling pathway. Here, PDGFRB is linked to pulmonary arterial hypertension.