1. Department of Otolaryngology-Head and Neck Surgery, International University of Health and Welfare, Tokyo, Japan
2. Department of Otolaryngology-Head and Neck Surgery, Jichi Medical University, Shimotsuke, Japan
3. Department of Otolaryngology/Head and Neck Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
4. Department of Tumor Pathology, Hamamatsu University School of Medicine, Hamamatsu, Japan
5. Department of Neurosurgery, Jichi Medical University Saitama Medical Center, Saitama, Saitama, Japan
6. Laboratory of Head and Neck Center Biology, Department of Otolaryngology, Head and Neck Surgery, The University of Michigan, Ann Arbor, MI, USA