1. The University of Edinburgh, School of Biological Sciences (CSE) and School of Biomedical Sciences (CMVM), CH Waddington Building, 3.07, The King’s Buildings, Mayfield Road, Edinburgh EH9 3JD, U.K.
2. Department of Cell Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037