1. Department of Microbiology and Immunology, The University of Melbourne, Victoria 3010, Australia
2. Department of Cell Biology, Division of Vascular Biology, The Scripps Research Institute, La Jolla, California 92307
3. The Department of Medicine and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, and Northport VAMC, Northport, New York 11794
4. Celltech Group plc., Slough SL1 4EN, United Kingdom