Nature Reviews Molecular Cell Biology 20, 5–20 (2019) https://doi.org/10.1038/s41580-018-0059-1 Published online 18 September 2018

The legend of Figure 2 neglected to acknowledge that part b was adapted with permission from ref.46, Elsevier and that part d, third panel from the left was reproduced from ref.62, Springer Nature Limited. The change has been made in the HTML and PDF versions of the manuscript.