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Competing Interests

The authors declare that they have no competing interests.

Author Contributions

Yazhong Zhu conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.

Shunyi Li conceived and designed the experiments, reviewed drafts of the paper.

Yimeng Luo reviewed drafts of the paper.

Hongye Ma reviewed drafts of the paper.

Yan Wang contributed reagents/materials/analysis tools.

Patent Disclosures

The following patent dependencies were disclosed by the authors:


Data Deposition

The following information was supplied regarding data availability:

The research in this article did not generate any raw data.


Financial support was provided by the National Natural Science Foundation of China (NO.U1304216), the Research Fund of Yong Scholars for the Doctoral Program of Higher Education of China (Grant No. 20124101120015), and the Foundation of He’nan Educational Committee (Grant No. 13A610689). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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