1. Department of Biological Sciences and the Walther Cancer Institute, University of Notre Dame, Notre Dame, IN 46556
2. Institut fur Experimentelle und Klinische Pharmakologie und Toxikologie der Albert-Ludwigs-Universitat Freiburg, D-79104 Freiburg, Germany
3. Membrane and Cytoskeleton Dynamics Group, Institute Curie, 75248 Paris, France