Nat. Cell Biol. 14, 148–158 (2012); published online 18 December 2011; corrected after print 25 January 2012

In the version of this article initially published online and in print, the y-axis label for the graph in Figure 6b was incorrect. The correct label for the axis is “Normalized Ras–GTP”. This error has been corrected online in both the HTML and PDF versions of the article.