McGill University - Department of Biochemistry, University of Cambridge - Gurdon Institute, Max Planck Institute for Molecular Cell Biology and Genetics, McGill University - Department of Biochemistry, University of California, Los Angeles (UCLA) - Department of Biological Chemistry, Max Planck Institute for Molecular Cell Biology and Genetics, McGill University - Department of Biochemistry, University of California, Los Angeles (UCLA) - Department of Biological Chemistry, Max Planck Institute for Molecular Cell Biology and Genetics, University of Cambridge - Wellcome Trust/Cancer Research UK Gurdon Institute and McGill University - Department of Biochemistry