About the Authors
Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan
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: YJL YHS. Performed the experiments: YJL. Analyzed the data: YJL YHS. Contributed reagents/materials/analysis tools: YJL YHS. Wrote the paper: YJL YHS.