KIT and idiopathic pulmonary arterial hypertension: SCF and c-Kit play a role in vascular disease and repair as suggested by enhanced expression of c-Kit by resident cells, as well as recruitment of circulating c-Kit-positive cells in various vascular pathologies including atherosclerosis [12, 13], in-stent restenosis [14], restenosis of artificial vessel grafts [15], aortic aneurysms [16], idiopathic pulmonary arterial hypertension [17] and aging [18].