1. Sangamo Biosciences, Point Richmond Technology Centre, 501 Canal Boulevard, Suite A100; Richmond CA 94804 USA
2. Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Building 18T, Room 106; Bethesda MD 20892 USA
3. Present address: Department of Biology, Trent University; Peterborough Ontario Canada
4. Present address: Laboratoire de Physiologie, MNHN, UMR CNRS; Paris France
5. Institute of Molecular Pathology, Dr. Bohr-Gasse 7; Vienna A-1030 Austria