1. Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 660–701, South Korea
2. Department of Pathobiology, Small Animal Tumor Diagnostic Center, College of Veterinary Medicine, Konkuk University, Seoul 143–701, South Korea
3. Department of Cell and Developmental Biology, School of Dentistry, DRI and Brain Korea 21 Program, Seoul National University, Seoul 110–749, South Korea