1. Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4
2. Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
3. Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5S 1A8
4. Department of Medical Genetics and Microbiology, University of Toronto, Toronto, Ontario, Canada M5S 1A8 and Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada M5G 1L6
5. Institute for Systems Biology, Seattle, Washington 98105
6. Biotechnology Laboratory, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3