Nature Communications 5: Article number: 3562 (2014); Published 15 April 2014; Updated 21 March 2017

This Article is retracted by the authors. Nature Communications previously issued an Editorial Expression of Concern (http://www.nature.com/articles/ncomms13310) related to this Article, following the publication of a report commissioned by The Karolinska Institute and prepared by the Expert Group for Misconduct in Research at the Swedish Central Ethical Review Board. Owing to the technical issues raised by this investigation, we, the authors, are now retracting the Article.

P.M., S.S., Y.G., S.B., M.A.B., C.D.G., A.S., K.K., H.K., P.D., A.B., R.H., D.R., C.I., B.J. and D.A.T. agree with this retraction. P.J., M.L.L., J.H., G.L., A.B.R., H.U. and Y.Z. could not be reached for comment.