Nature Cell Biol. 11, 1241–1246 (2009); published online 6 September 2009; corrected after print 15 October 2009

In the version of this letter initially published online and in print, the following sentence and reference were omitted. This error has been corrected in both the HTML and PDF versions of the article.

“However, a recent study has also reported that cofilin oxidation impairs its cytoskeletal function in T cells28.”