This study tested the hypothesis that Jagged2/Notches promoted the endothelial‐mesenchymal transition (endMT)‐mediated pulmonary arterial hypertension (PAH) (i.e. induction by monocrotaline [MCT]/63 mg/kg/subcutaneous injection) through increasing the expression of GATA‐binding factors which were inhibited by propylthiouracil (PTU) (i.e. 0.1% in water for daily drinking since Day 5 after PAH induction) in rodent. Here, JAG2 is linked to pulmonary arterial hypertension.