They found that HPMECs from PAH patients responded to BMP9 stimulation, exhibiting an 8‐fold increase in BMPR2 levels, differing from the response observed in PAECs and endothelial colony‐forming cells (ECFCs), thus suggesting that the lung tissue microenvironment could affect activation and outcome of BMP‐dependent signaling pathways in PAH. Here, GDF2 is linked to pulmonary arterial hypertension.