1. Department of Cytopathology, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan
2. Department of Biochemistry, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan
3. Department of Immunology, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan
4. Riken Vitamin Co., Ltd., Tokyo, Japan