1. Department of Biological Sciences, Columbia University, New York, New York 10027, United States
2. Department of Radiation Oncology, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York 10032, United States
3. Radiological Research Accelerator Facility, Center for Radiological Research, Columbia University, Irvington, New York 10533, United States
4. Department of Neurological Surgery, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York 10032, United States
5. Departments of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, 1130 St. Nicholas Ave Rm.1001, New York, New York 10032, United States
6. Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, New York 10032, United States
7. Department of Chemistry, Columbia University, New York, New York 10027, United States