[1] UNIV TORONTO, DEPT MED GENET, TORONTO M5S 1A1, ONTARIO, CANADA
[2] HOSP SICK CHILDREN, DEPT BIOCHEM, TORONTO M5G 1X8, ONTARIO, CANADA
[3] ENEA CASACCIA, DIV BIOPHYS & BIOMED SCI, Rome, ITALY
[4] LUDWIG INST CANC RES, JOINT PROT STRUCT LAB, MELBOURNE, AUSTRALIA