1. Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
2. Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
3. Department of Anatomy, Howard University College of Medicine, Washington, DC 20059, USA
4. Department of Biological Physics, Eotvos University, Budapest 1117, Hungary
5. Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS (UMR 7104), Inserm U964, Université de Strasbourg, Illkirch Graffenstaden 67400, France