Nat. Med. 18, 589–594 (2012); published online 4 March 2012; corrected after print 4 May 2012

In the version of this article initially published, it was incorrectly stated that the mice were fed a diet supplemented with α-tocopherol at 600 mg per kg of body weight. Instead, the food itself contained 600 mg of α-tocopherol per kg. The error has been corrected in the HTML and PDF versions of the article.