About the Authors

Kimberly J Reese

Affiliation Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

Shu Lin

Affiliation Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

Raluca I Verona

Affiliation Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America

Richard M Schultz

Affiliation Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America

Marisa S Bartolomei

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

Affiliation Department of Cell and Developmental Biology, 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

KJR, RMS, and MSB conceived and designed the experiments. KJR, RIV, and SL performed the experiments. KJR analyzed the data with input from SL, RIV, RMS, and MSB. KJR wrote the paper with editing and other suggestions from RMS and MSB.