1. Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada.
2. Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 3E1, Canada.
3. Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
4. Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.
5. Center for Analysis of Evolution and Function, University of Toronto, Toronto, Ontario, Canada.
6. Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany.
7. Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
8. Cell Morphogenesis and Signal Transduction, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
9. Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.