1. Department of Biochemistry; College of Life Science and Biotechnology; Yonsei University; Seoul 03722 Korea
2. Biomedical Research Institute; Seoul National University Hospital; Seoul 110-744 Korea
3. Severance Biomedical Science Institute and BK21 PLUS Project to Medical Sciences, Severance Institute for Vascular and Metabolic Research; Gangnam Severance Hospital Yonsei University College of Medicine; Seoul 06230 Korea
4. School of Mechanical Engineering; Korea University; Seoul 02841 Korea