1. Department of Obstetrics and Gynecology, Sapporo Medical University School of Medicine, Sapporo, Japan
2. Department of Cell Science, Institute of Cancer Research, Sapporo Medical University School of Medicine, Sapporo, Japan
3. Department of Otolaryngology, Sapporo Medical University School of Medicine, Sapporo, Japan
4. Department of Thoracic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan