8 embryos collected at E8.5 were dissociated in Trypsin 0.25% EDTA 1mM for 5 min at RT, washed in PBS and cross-linked with 1 % formaldehyde for 10 min at RT. After sonication with a Bioruptor waterbath sonicator (Diagenode), we performed ChIP with the LowCell ChIP kit (Diagenode). ChIP-Seq libraries were prepared with the NEXTflex ChIP-Seq Kit (Bioo Scientific) according to the manufacturer’s instructions.