1. Department of Genetics, Life Sciences Institute, Hebrew University Jerusalem 91904 Israel
2. Department of Pediatrics, Soroka Medical Center, Ben‐Gurion University Beer‐Sheva 84141 Israel
3. Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599‐7248 USA
4. Department of Anatomy and Cell Biology, Institute for Molecular Medicine, Uniformed Services University School of Medicine (USUHS) Bethesda Maryland 20814 USA