Nat. Biotechnol. 32, 507 (2014); published online 9 June 2014; corrected after print 18 June 2014
In the version of this article initially published, a headshot of Floyd Romesberg incorrectly appeared next to a quote from Tony Wyss-Coray. The error has been corrected in the PDF version of the article.
The online version of the original article can be found at 10.1038/nbt0614-507b