NKX2-5 and pulmonary arterial hypertension: We have thus shown that vascular remodeling is associated with unexpected NKX2-5 reactivation in vascular cells, in 3 separate settings: in vitro in HPASMCs and in 2 separate, established in vivo models of PAH, one driven by hypoxia and the other driven by TGF-β superfamily signaling and vascular injury.