1. Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD;
2. Maryland Pathogen Research Institute, College Park, MD;
3. Institute for Bioscience and Biotechnology Research, Rockville, MD;
4. National Institute of Standards and Technology, Rockville, MD;
5. Department of Biochemistry, School of Medicine, Boston University, Boston, MA; and
6. Department of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA