1. Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA.
2. Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA.
3. Department of Pathology and Laboratory Medicine and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
4. The Howard Hughes Medical Institute and the Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA.
5. Electrical and Computer Engineering Department, University of California, Santa Barbara, CA 93106, USA.
6. Program in Developmental and Stem Cell Biology, University of California, San Francisco, CA 94158, USA.
7. Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Ludwigstr. 43, 61231 Bad Nauheim, Germany.