1. Cell Dynamics Research Center, Research Center for Biomolecular Nanotechnology, School of Life Sciences, Gwangju Institute of Science and Technology, 261 Chemdan-gwagiro, Gwangju 500-712, Republic of Korea
2. Department of Diagnostic Radiology, Chonnam National University Hwasun Hospital, 160 Ilsim-ri, Hwasun-eup, Jeonnam 519-809, Republic of Korea