Correction to: Nature Biotechnology https://doi.org/10.1038/s41587-020-0465-8, published online 6 April 2020.

In the version of this article initially published online, the Data Availability section listed the Single Cell Portal (https://portals.broadinstitute.org/single_cell). It has been revised to give Single Cell Portal accession numbers SCP424, SCP425 and SCP426. The change has been made in the print, PDF and HTML versions of the article.