1. Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, 00290 Helsinki, Finland
2. Department of Biochemistry and Biocenter Oulu, University of Oulu, 90014 Oulu, Finland
3. Institute of Biotechnology, University of Helsinki, 00290 Helsinki, Finland
4. Blood Research Institute, Blood Center of Wisconsin, Milwaukee, Wisconsin 53266