Nat. Immunol. 13, 105–108 (2012); published online 19 January 2012; corrected after print 3 February 2012

In the version of this article initially published, the first author's surname was incorrect and e-mail address was missing. The correct name is “Gomez-Cambronero”; the e-mail address is julian.cambronero@wright.edu. The error has been corrected in the HTML and PDF versions of the article.