In the version of this article initially published, in Fig. 2a, the image showing the parental (WT) SNU466 cells was mistakenly a duplicate of the adjacent image of Cas9-expressing SNU466 cells. The image has been corrected, and the raw microscopy data have been made available at https://figshare. com/projects/Cas9_activates_the_p53_pathway_and_selects_for_p53-inactivating_mutations/81080. The ‘Data availability’statement has been updated to include this URL. The SNU466 imaging data have consequently been reanalyzed, and the bar plots of γH2AX-positive cells in Fig. 2b have been replotted. The revised analysis yielded highly similar results to the original analysis: Cas9-expressing SNU466 cells exhibited a significantly higher fraction of γH2AX-positive cells than their parental cells; the P value for SNU466 has consequently been revised from 0.0041 to 0.009. In all analyses, the parental and Cas9-expressing cells from each experiment were analyzed together, with the same fluorescence exposure and color intensity thresholds to enable a fair comparison. The original and corrected Fig. 2 panels are shown below. This error did not affect any other analyses or conclusions.

In Fig. 1d, the bands for EFM192A and MDAMB453 came from two different gels (which were run together): one for the housekeeping protein and one for the other proteins; only one gel was originally shown in the Source Data for Fig. 1. Figure 1d has been revised to show all the bands from a single gel, and the Source Data file for Fig. 1 has been updated accordingly. The original and corrected Fig. 1d is shown below. This error did not affect the protein-level quantification in Fig. 1e or any other analyses or conclusions.