HMOX1 and cystic fibrosis: Since the maximum induction of HO-1 was observed between 3 and 6 h after systemic PP-007 administration (Fig. 4a), WT and CF mice were pretreated intravenously (IV) with a single dose of PP-007 (320 mg/kg) or vehicle alone for 6 h and then nebulized with PA-LPS for three consecutive days.