Lung overexpression of prostacyclin synthase is protective including in models of pulmonary hypertension,61 and while this nonspecific delivery is clearly effective, in light of our findings, we suggest that, to maximize the efficacy and reduce the systemic side effects, prostacyclin synthase delivery approaches would best be targeted to the pulmonary endothelium. This evidence concerns the gene PTGIS and pulmonary hypertension.