1. Edwin L. Steele Laboratory, Department of Radiation Oncology, MGH Cancer Center, Massachusetts General Hospital, 100 Blossom Street, Boston, MA 02114, USA.
2. Harvard Medical School, Boston, MA 02115, USA.
3. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA.
4. Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20814, USA.