MST1 and pulmonary arterial hypertension: The inactivation of Hippo could induce proliferation and suppress apoptosis in pulmonary arterial smooth muscle cells (PASMCs), which is one of the most important factors in vasculature remodelling in pulmonary arterial hypertension.306,307 Interestingly, recent research revealed that MST1/2, a Hippo component that usually plays an antiproliferative role, supports the abnormal proliferation of PASMCs in pulmonary arterial hypertension via forehead homeobox type O and BUB3.308