Nat. Chem. Biol. 13, 111–118 (2017); published online 21 November 2016; corrected after print 17 March 2017

In the version of this article initially published, Figure 1 was missing the ring designation letters, the substituent designation (R1/R2) and the ring locant numbers for the compounds in panel a. The error has been corrected in the HTML and PDF versions of the article.