IL6 and pulmonary arterial hypertension: Moreover, the exposure to PAH model-derived EVs causes the in vitro and in vivo upregulation of IL-6, endothelin-1, erythropoietin receptor [149], ROS accumulation and induces the transcription and release of VEGF-A, FGF2 and VEGFR-1 and tube formation in PAECs [148].