About the Authors

Derek Lessing

Affiliation Department of Biology, University of Pennsylvania, Howard Hughes Medical Institute, Philadelphia, Pennsylvania, United States of America

Nancy M Bonini

To whom correspondence should be addressed. E-mail: nbonini@sas.upenn.edu

Affiliation Department of Biology, University of Pennsylvania, Howard Hughes Medical Institute, Philadelphia, Pennsylvania, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

NMB directed the screen and performed initial studies on Atx2. DL and NMB conceived and designed the experiments, and wrote the paper. DL performed and analyzed the experiments.