About the Authors
Division of Stem Cell Biology and Developmental Genetics, Medical Research Council, National Institute for Medical Research, London, United Kingdom
The authors have declared that no competing interests exist.
Conceived and designed the experiments: SG RL-B JMAT. Performed the experiments: SG. Analyzed the data: SG JMAT. Contributed reagents/materials/analysis tools: SG RL-B JMAT. Wrote the paper: SG RL-B JMAT.