1. Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Okayama, Japan
2. Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama, Japan
3. Department of Diagnostic Pathology, Hyogo Cancer Center, Akashi, Hyogo, Japan
4. Department of Pathology, Okayama University Hospital, Okayama, Okayama, Japan