Nat. Chem. Biol. 10, 487–488 (2014); published online 17 June 2014; corrected after print 30 June 2014

In the version of this article initially published, the surname of the first author in reference 2 was misspelled as Pfaffender. The correct spelling is Pfaffeneder. The error has been corrected in the HTML and PDF versions of the article.