SMURF1 and pulmonary arterial hypertension: In addition, miR-140-5p expression was reduced in rat models in vivo and in PAH patients, and knockdown of miR-140-5p could facilitate the expression of the E3 ubiquitin ligase SMURF1 and activate BMP signaling, thereby promoting PASMC proliferation and pulmonary artery endothelial dysfunction and possibly exacerbating PAH (113).