Nature Reviews Molecular Cell Biology (2018) https://doi.org/10.1038/s41580-018-0052-8 Published online 24 August 2018

In the original version of the article, sentences highlighting references 108, 137 and 175 incorrectly refer to other items in the reference list: reference 106, 132 and 169, respectively, which were corrected — in order — to reference 110, 136 and 176. The changes have been made in the HTML and PDF versions of the manuscript.