About the Authors
Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
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: SYW JS DSS LSK. Performed the experiments: SYW JS DSS. Analyzed the data: SYW JS DSS. Contributed reagents/materials/analysis tools: SYW JS DSS. Wrote the paper: SYW LSK.