Nature Reviews Endocrinology (2018) https://doi.org/10.1038/s41574-018-0145-7 Published online 14 December 2018

In the original version of this manuscript, the incorrect names for two proteins were given. S1P and S2P should have been defined as site-1 protease and site-2 protease. This has been corrected in the HTML and PDF versions of the manuscript.