Nature 485, 507–511 (2012); doi:10.1038/nature11058

It has been brought to our attention that there is an error in Supplementary Fig. 1b, owing to incorrect assembly of the image. The correct panel and figure legend (and the raw data used to generate Supplementary Fig. 1b) are shown in the Supplementary Information to this Corrigendum.

We would also like to clarify that the antibody used in Fig. 2e of the original Letter is Millipore mab1637. This antibody reacts with the C terminus of the neuron-specific β III isoform of β-tubulin. It does not identify β-tubulin in glial or non-neuronal cells, hence the absence of tubulin bands in control HeLa cells.