1. Neuromuscular and Cardiovascular Cell Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany (M.H.R., C.P., C.F., M.G.).
2. DZHK: German Centre for Cardiovascular Research, Partner Site, Berlin, Germany (M.H.R., M.G.).
3. Department of Cellular and Molecular Medicine, University of Arizona, Tucson (M.M., H.G.). The current affiliation for P.S. and T.S. is Department of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg University Mainz, Germany.