ChIP-seq data sets for four histone marks (H3K4me1, H3K4me3, H3K27ac, and H3K27me3—Abcam ab8895, ab8580, ab4729, and Millipore 07-449, respectively) were generated for E11.5 limbs, while for E11.5 forebrain we produced ChIP-seq for H3K4me1, H3K4me3, and H3K27ac and used a previously generated H3K27ac data set (Nord et al. 2013 (link)). Histone ChIP-seq was carried out using previously described protocols (Bernstein et al. 2006 (link)). DNA libraries were prepared, sequenced, and analyzed as described for FLAG ChIP-seq. All histone data sets were generated with an input control.