BM-derived progenitors from PAH patients can induce vascular remodeling, including in situ thrombi, in the pulmonary arteries of mice [27]._ENREF_15_ENREF_30 In the present study, we concentrated on the role of cells expressing the tyrosine kinase receptor c-kit: c-kit is a common marker of primitive progenitor and stem cells, including the recently described lung stem cells [12] and rare vascular endothelial stem cells [13]. Here, NTRK1 is linked to pulmonary arterial hypertension.