Since we also observed GCN2 hyperphosphorylation in pulmonary vascular SMCs in MCT rats and patients with IPAH, it is possible that GCN2 can also be activated by other PAH-causing factors, such as growth factors or inflammatory mediators (51), to promote pulmonary vascular remodeling and PAH development. The gene discussed is EIF2AK4; the disease is pulmonary arterial hypertension.