1. Department of Medical Biophysics, Ontario Cancer Institute, University of Toronto, Toronto, Ontario, Canada M5G 2C1
2. Institute for Molecular Biotechnology of the Austrian Academy of Sciences, A-1030 Vienna, Austria
3. Program in Developmental Biology, The Hospital for Sick Children, and Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, Canada M5G 1X8
4. Regulation of Protein Function Laboratory, National Cancer Institute—Frederick, NIH, Frederick, Maryland 21702