About the Authors

Sergio Ruiz

Affiliation Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America

Kristen Brennand

Affiliation Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California, United States of America

Athanasia D. Panopoulos

Affiliation Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America

Aída Herrerías

Affiliation Center of Regenerative Medicine in Barcelona, Barcelona, Spain

Fred H. Gage

Affiliation Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California, United States of America

Juan Carlos Izpisua-Belmonte

belmonte@salk.edu

Affiliations Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America, Center of Regenerative Medicine in Barcelona, Barcelona, Spain

Competing Interests

Sanofi-Aventis provided funding for this study. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: SR JCIB. Collection and assembly of data: SR KB ADP AH. Analyzed the data: SR KB ADP AH FHG JCIB. Wrote the manuscript: SR KB ADP JCIB.