Nature 481, 511–515 (2012); doi:10.1038/nature10758

In this Letter, information was inadvertently omitted that the results in Supplementary Fig. 21 represent the mean + s.e.m. for 4–5 mice per group. We also note that the samples used for Fig. 3f, Supplementary Figs 3 and 13a were derived from the same experiment, and that the gels/blots were processed in parallel. Equal concentrations of protein were loaded on all gels. The same actin loading control gel is shown in Fig. 3f, Supplementary Figs 3 and 13a. Furthermore, owing to a production error at the proof stage, the time point labels were missing from Fig. 1e. After ‘Exercise (min)’, the labels should read 0, 15 and 30. This has now been corrected in the PDF and HTML versions of the paper. None of these changes alters the conclusions of the paper.