1. Cell and Developmental Biology Department, Centre for Genomic Regulation, Barcelona Institute for Science and Technology, 08003 Barcelona, Spain
2. Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720
3. Universitat Pompeu Fabra, 08002 Barcelona, Spain
4. Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94143
5. Institute for Human Genetics, University of California, San Francisco, San Francisco, CA 94143
6. Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain