Correction to: Nature Reviews Molecular Cell Biology https://doi.org/10.1038/s41580-021-00447-6, published online 25 January 2022.

In the version of this article initially published, the technique fastGRO was presented in Fig. 2 and the main text as a chromatin-based run-on technique when in fact it is a nuclear run-on technique. Accordingly, in Fig. 2, right-hand “Techniques” section, the third balloon has been edited to include “fastGRO” and the seventh balloon edited to remove “fastGRO,” and the eighth sentence of the Fig. 2 legend has been amended to include fastGRO, as follows: “Nucleus: transcription run-on (TRO) analyses are performed in biochemically isolated nuclei using 5-bromouridine 5′-triphosphate (BrUTP) in GRO-seq37, 4-thiouridine (4sU) in fastGRO40 or biotin-labelled NTPs (biotin-NTP) in PRO-seq38.” Further, the penultimate sentence of the “In vitro RNA labelling” section has been amended to read “Finally, a variation on genomic TRO called fastGRO also employs 4-thiouridine (4sU) in the NRO reaction” (from the original “Finally, a variation on genomic TRO called fastGRO also employs the use of chromatin fractions as starting material but the nascent transcript is tagged with 4-thiouridine (4sU)….”). The changes are reflected in the HTML and PDF versions of the article.