JAK2 and pulmonary arterial hypertension: In general, there is a PASMC phenotype switch from a differentiated state to a proliferative state during the course of PAH development.31 To further confirm the above data observed in animals, we employed TG‐101348 (also named Fedratinib, thereafter referred to as TG), a selective JAK2 inhibitor,32 to pre‐treat HPASMCs for 1 hour, followed by hypoxic insult for 24 hour.