1. Institut für Zellbiologie, Rheinische Friedrich‐Wilhelms‐Universität Bonn Ulrich‐Haberland‐Strasse 61a D‐53121 Bonn Germany
2. Department of Cell and Developmental Biology, School of Medicine, University of North Carolina Chapel Hill NC 27599‐7090 USA
3. Program in Molecular Cardiology and the Lineberger Comprehensive Cancer Center, University of North Carolina Chapel Hill NC 27599‐7075 USA