HIF1A and idiopathic pulmonary arterial hypertension: However, some studies indicate that the protein expression of HIF-1α in PASMCs of IPAH patients is decreased, leading to an increase in contractile force.112,113 Conversely, transfecting Hif-1α can reduce this contractile force,112 highlighting the need to consider the specific type of PH when implementing HIF-targeted therapies.