Selective CXCR4 antagonist, promoting inhibition of the SDF-1/CXCR4 axis, which significantly improved lung alveolarization and decreased pulmonary hypertension, right ventricular hypertrophy, vascular remodeling, vascular cell proliferation, and lung or right ventricular stem cell expressions in murine model. The gene discussed is CXCR4; the disease is pulmonary arterial hypertension.