library_construction_protocol: Neural folds were dissected from HH7-7 embryos (n=20 per CUT&RUN experiment). Cells were dissociated in Accumax for 20min at RT under mild agitation. CUT&RUN experiments were carried out as previously described (Rothstein and Simoes-Costa, 2019). CUT&RUN libraries were prepared using the NEBNext Ultra II DNA Library Prep Kit (New England Biolabs, E7645) and sequenced with paired-end 37bp reads on an Illumina NextSeq500 instrument.