Another balloon overstretch experiment conducted by Mallawaarachchi et al. demonstrated that PAAFs are activated to myofibroblasts by stretch in PAH, migrate towards the lumen to form the neointima, and synthesize ECM after vascular injury mediated by the TGF-β1 pathway (Mallawaarachchi et al. 2005). The gene discussed is TGFB1; the disease is pulmonary arterial hypertension.