1. Department of Cell and Developmental Biology College of Dentistry Seoul National University Seoul 110-749 Korea
2. National Creative Research Initiatives Center for Endothelial Cells Department of Life Science Pohang University of Science and Technology Pohang 790-784 Korea
3. Research Institute of Medical Sciences Chonnam National University Gwangju 501-190 Korea
4. National Research Laboratory for Bone Metabolism School of Dentistry Chosun University Gwangju 501-759 Korea