1. Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh EH16 4SB, UK.
2. Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh EH16 4SB, UK.
3. Taube-Koret Center, Hellman Program, and Rodenberry Stem Cell Program, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA.
4. Departments of Neurology and Physiology, University of California, San Francisco, San Francisco, CA 94143, USA.
5. Institute of Psychiatry, Medical Research Council Centre for Neurodegeneration Research, King’s College London, London SE5 8AF, UK.
6. Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
7. Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
8. Yale Stem Cell Center, Department of Genetics, Yale School of Medicine, New Haven, CT 06520, USA.
9. Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
10. Department of Biological Chemistry and Molecular Pharmacology, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA.
11. Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK.