1. Department of Molecular Biology, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan
2. Department of Oral Surgery, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan
3. Department of Otolaryngology-Head and Neck Surgery, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan
4. Department of Pathology, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan
5. Department of Head and Neck Oncology, Sapporo Teishinkai Hospital, Sapporo 065-0033, Japan
6. Department of Cell Science, Research Institute of Frontier Medicine, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan