1. Department of Molecular Pathology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan
2. Division of Carcinogenesis and Cancer Prevention, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan
3. Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, Hadano, Kanagawa, Japan
4. Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kawasaki-ku, Kawasaki, Kanagawa, Japan
5. Association for Promotion of Research on Risk Assessment, Nakagawa-ku, Nagoya, Japan