Jane E. Visvader1, Jeffrey M. Rosen2 and Samuel Aparicio3 1The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia 2Baylor College of Medicine, Houston, Texas 77030, USA 3University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada Correspondence: visvader{at}wehi.edu.au