Dissociated motor neurons were clarified from sonicated nuclei and histone-DNA complexes were isolated with H3K27me3 antibody Libraries were prepared according to Illumina's instructions accompanying the KAPA TruSeq DNA library prep kit (KK8201). Briefly, DNA was end-repaired by using End Repair Mix (ERP). After adapter ligation DNA was PCR amplified with Illumina primers for 12 cycles and library fragments of ~300 bp (insert plus adaptor and PCR primer sequences). The purified DNA was captured on an Illumina flow cell for cluster generation. Libraries were sequenced on the Genome Analyzer following the manufacturer's protocols.