To examine if Areg plays a role in the pathogenesis of chronic neonatal lung injury, we initially quantified the expression of Areg mRNA in the whole lungs from neonatal WT mice exposed to 70% O2 from P1 to P14, a widely established model of HO-induced experimental BPD [29]. The gene discussed is AREG; the disease is bronchopulmonary dysplasia.