About the Authors

Ping An

Affiliation Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America

Paula J Grabowski

To whom correspondence should be addressed. E-mail: pag4@pitt.edu

Affiliation Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

PA and PJG conceived and designed the experiments, analyzed the data, and wrote the paper. PA performed the experiments.