Snap frozen skin samples from WT and Irf6-/- E16.5 mouse embryos (200 mg, n = 2 of each genotype) were sent to Active Motif for ChIP-Seq. ChIP was performed with validated antibodies against H3K27me3 (Active Motif 39155), H3K27Ac (Active Motif 39133) or H3K4me3 (Active Motif 39159). Illumina sequencing libraries were prepared from the ChIP and input DNA using the standard consecutive enzymatic steps of end-polishing, dA-addition, and adaptor ligation using Active Motif's custom liquid handling robotics pipeline. After the final 15 cycle PCR amplification step, the resulting DNA libraries were quantified and sequenced on NextSeq 500. Libraries were prepared using standard protocols for the Ovation Ultralow System. Briefly, samples were PCR-amplified and sized using the Agilent 2100Bioanalyzer. Barcoded libraries were sequenced 50 bp single end on HiSeq 2500 (Illumina).