ACVR2A and pulmonary arterial hypertension: The ability of ActRIIA-Fc to reverse established pulmonary inflammation and cardiopulmonary remodeling in severe experimental PAH indicates that the SMAD2/3-pathway ligands targeted by this agent mediate key interactions between cell types implicated in this disease, potentially including perivascular immune cells, endothelial cells, vascular smooth muscle cells, and adventitial fibroblasts.