Given that many signaling pathways are involved in PAH, such as the mitogen-activated protein kinase (MAPK) and AKT signaling pathways (J. Dai et al., 2018; Y. Guo et al., 2020b), we wondered whether IRF9 could regulate these pathways to affect the proliferation of PASMCs. The gene discussed is IRF9; the disease is pulmonary arterial hypertension.