Studies have shown that a group of HDACs, including HDAC1, HDAC2, and HDAC3, are upregulated in pulmonary vascular cells from PAH patients and animal models, and that HDAC inhibitors can effectively suppress pro-inflammatory mediator production, reduce cell proliferation, and ameliorate vascular remodeling (127). The gene discussed is HDAC9; the disease is pulmonary arterial hypertension.