In the originally published version of this article, in the legend to Figure S1 (which relates to main Figure 1C), the definition of TERT status in cell lines as “wt, wild type promoter with biallelic expression” should instead be “wt, wild type promoter; some of these are BAE (N = 43; Huang et al., 2015) and some are undetermined.” This correction does not change any of the stated conclusions of our paper but is reported here so that others using these cell lines will not be misled. The authors regret this error.