About the Authors
Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, Rhode Island, 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: JG JK KM. Performed the experiments: JG JK EP TW. Analyzed the data: JG JK EP TW KM. Wrote the paper: JG EP KM.