1. Centre for Cancer Biomedicine, University of Oslo and Department of Biochemistry, The Norwegian Radium Hospital, Montebello, N-0310 Oslo, Norway
2. Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, New York, NY 10032
3. Department of Neurodegenerative Disease
4. MRC Prion Unit, Institute of Neurology, University College London, London WC1N 3BG, England, UK