Nat. Cell Biol. 13, 1282–1288 (2011); published online 2 November 2011; corrected after print 29 April 2015

In the version of this Review originally published the authors inadvertently omitted a key reference. This has now been added to the caption of Fig. 3 in the online version: 'The actin-binding protein WASP has been discovered in the nucleus and modulates transcription independently or with the ARP2/3 complex97.'