1. Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
2. Department of Life Science, National Taiwan University, Taipei 10617, Taiwan, Republic of China
3. Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, People's Republic of China
4. Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA