1. Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
2. Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA.
3. Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.
4. Promega Corporation, Madison, WI 53711, USA.
5. Departments of Pathology and Dermatology, University of Michigan, Ann Arbor, MI 48109, USA.
6. Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA.