About the Authors

Roman Biek
Peter D Walsh
Eric M Leroy
Leslie A Real

To whom correspondence should be addressed. E-mail: lreal@emory.edu

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

RB, PDW, and LAR conceived and designed the experiments. RB analyzed the data. EML contributed reagents/materials/analysis tools. RB, PDW, EML, and LAR wrote the paper.