Rat pups that receive a single intraperitoneal injection of tunicamycin develop a BPD phenotype characterized by alveolar simplification, increased apoptosis, myeloid cell infiltration, decreased capillary count, and increased myeloperoxidase (MPO) expression in the lungs reminiscent of HOX-induce BPD rat lungs [16]. Here, MPO is linked to bronchopulmonary dysplasia.