1. Department of Anatomy and Cell Biology, University of Iowa School of Medicine, Iowa City, IA 52242.
2. Center for Gene Therapy of Cystic Fibrosis, University of Iowa School of Medicine, Iowa City, IA 52242.
3. Department of Surgery, University of Iowa School of Medicine, Iowa City, IA 52242.
4. Department of Pediatrics, University of Iowa School of Medicine, Iowa City, IA 52242.
5. Cystic Fibrosis/Pulmonary Research and Treatment Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
6. Department of Laboratory Medicine and Pathobiology, Hospital for Sick Children and University of Toronto, Toronto, ON M5G 0A4, Canada.
7. Department of Internal Medicine, University of Iowa School of Medicine, Iowa City, IA 52242.