1. Basic Sciences and Computational Biology, Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Seattle, WA 98109, USA
2. Department of Genome Sciences, University of Washington, 3720 15th Ave NE, Seattle, WA 98195, USA
3. Howard Hughes Medical Institute, 1100 Fairview Ave N, Seattle, WA 98109, USA
4. Biozentrum, University of Basel, Spitalstrasse 41, Basel 4056, Switzerland
5. Swiss Institute of Bioinformatics, Lausanne 1015, Switzerl