In the present studies, we observed that endothelial FoxM1 is upregulated in the PVECs of IPAH patients and severe PH mouse model Egln1Tie2Cre mice, a mouse model with marked elevation of RVSP, severe RV hypertrophy, and obliterative vascular remodeling, resembling many pathological features of IPAH in patients. Here, FOXM1 is linked to idiopathic pulmonary arterial hypertension.