Nat. Immunol. 16, 458–466 (2015); published online 23 March 2015; corrected after print 20 April 2015

In the version of this article initially published, the staining intensity for the merged fluorescence microscopy did not match that in the single-staining panels in Figure 1c,e. The panels been replaced with the original staining intensities. The error has been corrected in the HTML and PDF versions of the article.