Nat. Biotechnol. 36, 297–306 (2018); published online 5 April 2018; corrected after print 15 May 2018

In the version of this article initially published, the name and photo of Viviane Tabar, one of BlueRock's founders, was omitted. A misplaced '&' in the author list in the PDF has been corrected, and the abbreviation MSKCC added in the text. The errors have been corrected in the HTML and PDF versions of the article.