About the Authors
National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
The authors have declared that no competing interests exist.
AJS conceived and designed the experiments and performed the experiments. AJS, RCA, and LMA analyzed the data. AJS and LMA contributed reagents/materials/analysis tools. AJS, RCA, and LMA wrote the paper.