About the Authors

Julia Y Lee

¤ Current address: Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania, United States of America

Affiliation Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

Marina Kozak

Affiliation Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

Joel D Martin

Affiliation Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

Erin Pennock

Affiliation Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

F. Brad Johnson

To whom correspondence should be addressed. E-mail: johnsonb@mail.med.upenn.edu

Affiliation Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

JYL and FBJ conceived and designed the experiments and analyzed the data. JYL, MK, JDM, FP, and FBJ performed the experiments. MK and FBJ contributed reagents/materials/analysis tools. JYL, MK, and FBJ wrote the paper.