In the version of this article initially published, Fig. 4 included some errors. In Fig. 4c, the color for the left bar in each set of three bars (green) was incorrect; the correct color is orange (H2AK119ub, as in key). In Fig. 4d, top row, the downward error bars for H3K27me3 in the top middle plot (Fgf11 B) were incorrect; the correct s.d. in the negative direction is smaller for each. In Fig. 4d, bottom row, the far left downward error bar for HA-dCas9 in the left plot (Fgf11 A) was incorrect; the correct s.d. in the negative direction is larger. The errors have been corrected in the HTML and PDF versions of the article. (Figure presented.).