1. Divisions of Molecular Biology and Cell Biology, and Center for Biomedical Genetics, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands.
2. Department Biologie I, Genetik, Ludwig‐Maximilians‐Universität, 80638 München, Germany.
3. Zentrum für Molekular Biologie der Universität Heidelberg, 69120 Heidelberg, Germany.