In the article by C. White et al. (Nat. Cell Biol. 7, 1021–1028; 2005), the error bars shown in the Supplementary Information Fig. S3d were incorrect.

Furthermore, the statistical analysis in Figs 4d and S3d was not adequately explained: the error bars represent standard deviations of the mean in three independent experiments for each clone and time point. This has been corrected online.