1. Department of Biologics Evaluation, Korea Food and Drug Administration, 194 Tongil-ro, Eunpyung-gu, Seoul, 122-704, Korea.
2. Department of Biotechnology, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, Korea.
3. Genetic Toxicology Division, National Institute of Toxicological Research, 5 Nokbun, Eunpyung-Gu, Seoul 122-704, Korea.