 cDepartment of Biochemistry, University of Toronto, Toronto, ON, Canada M0S 0A0; dDivision of Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada M0G 0A0; Find this author on Google Scholar Find this author on PubMed Search for this author on this site For correspondence: [email protected] [email protected] Lewis E. Kay aDepartment of Molecular Genetics, University of Toronto, Toronto, ON, Canada M0S 0A0; bDepartment of Chemistry, University of Toronto, Toronto, ON, Canada M0S 0A0; cDepartment of Biochemistry, University of Toronto, Toronto, ON, Canada M0S 0A0; dDivision of Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, Canada M0G 0A0; Find this author on Google Scholar Find this author on PubMed Search for this author on this site For correspondence: [email protected] [email protected] Edited by 