1. Division of Gene Function and Development, Roslin Institute, Roslin, Midlothian, Scotland.
2. Centre for Stem Cell Biology, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, UK.
3. D Floor East Block, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK.
4. Institute of Genetics, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK.
5. Centre for Regenerative Medicine, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB, UK.
6. Public University of Navarra, Department of Agriculture, Edif. Los Olivos, Campus de Arrosadía 31006, Pamplona, Spain.