Nat. Immunol. 10, 21–27 (2009); published online 17 December 2008; corrected after print 16 January 2009

In the version of this article initially published, the published online date is 17 January 2009 and the ovals indicating store-dependent channels in the bottom row of Figure 2 are blue. The published online date should be 17 December 2008 and the ovals should be black . The errors have been corrected in the HTML and PDF versions of the article.