1. Department of Biosystems Science and Engineering (D-BSSE), ETH Zurich, Mattenstrasse 26, CH-4058 Basel, Switzerland, 2Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada, 3Université de Lyon, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne, France, 4Faculty of Biology and BIOSS Center for Biological Signaling Studies, Albert-Ludwigs-Universität Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany