Lysates were clarified from sonicated nuclei and Meis1-DNA or Prep1-DNA complexes were isolated with specific antibodies. Libraries were prepared according to Illumina's instructions accompanying the TruSeq ChIP Sample Prep Kit, 48 Samples-Set A Box, (part # 15034288). Briefly, Input DNA (5-10 ng) was end-repaired using a combination of T4 DNA polymerase, E. coli DNA Pol I large fragment (Klenow polymerase) and T4 polynucleotide kinase. The blunt, phosphorylated ends were treated with Klenow fragment (32 to 52 exo minus) and dATP to yield a protruding 3- 'A' base for ligation of Illumina's adapters which have a single 'T' base overhang at the 3’ end. After adapter ligation DNA was PCR amplified with Illumina primers for 14 cycles. The resultant library fragments were ~300 bp. The purified DNA was captured on an Illumina flow cell for cluster generation. Libraries were sequenced on the HiSeq 2000 following the manufacturer's protocols.