1. Present address: Central Research Institute of BodiTech, Inc. Chuncheon,Kangwon-Do 200-160, South Korea
2. Present address: Department of Biological Sciences, Indiana University South Bend, South Bend, IN 46634, USA
3. Department of Cell Biology, University of Massachusetts Medical School,Worcester, MA 01655, USA
4. Present address: Department of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, VIC 3050, Australia