1. Kyoto Pharmaceutical University, 1 Misasagi-Shichono-cho, Yamashina-ku, Kyoto 607-8412, Japan
2. Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
3. Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-1 Ariake-ku, Tokyo 135-8550, Japan