Nature Reviews Molecular Cell Biology (2018) https://doi.org/10.1038/nrm.2017.103 Published online 22 November 2017

The legend of Figure 1 has been modified to remove misleading referencing to evolution. The title of the legend has been modified from ‘Evolutionary expansion of eukaryotic 5ʹ UTR lengths’ to ‘Interspecies variation in 5ʹ UTR lengths’; the first sentence of the legend has been modified from ‘The length of 5ʹ untranslated regions (UTRs) has increased in eukaryotes during evolution…’ to ‘The length of 5ʹ untranslated regions (UTRs) varies in eukaryotes…’. The changes have been made in the HTML and PDF versions of the manuscript.