About the Authors
Department of Genetics, University of Cambridge, Cambridge, United Kingdom
Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
The authors have declared that no competing interests exist.
The author(s) have made the following declarations about their contributions: Conceived and designed the experiments: LM JR SR. Performed the experiments: LM YSC. Analyzed the data: LM YSC SR. Wrote the paper: LM JR SR.