Correction to: Nature https://doi.org/10.1038/nature13261 Published online 11 May 2014

The authors have identified errors in a figure label and the Methods section. In Fig. 3, the second negative control was labelled “Tubulin” and should have been labelled “TUB”. Also, in the primer descriptions of the Methods, the primers described as “tubulin” should also have been labelled “TUB”. The authors thank the anonymous reader who caught this mislabelling and apologize for any confusion created. The original article has not been corrected online.