1. Swammerdam Institute for Life Sciences, Molecular Cytology, Science Park 904, 1098 XH Amsterdam, The Netherlands
2. Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain
3. Department of Cell Biology and Histology/CMO, Academic Medical Center, University of Amsterdam, Meibergdreef 1, NL-1100 DD Amsterdam, The Netherlands