anti-Ebf1 antibody (Abnova H00001879-M01) was used to pick up Ebf1- bound regions. DNA fragments were repaired to blunt ends by T4 DNA polymerase and phosphorylated with T4 Polynucleotide kinase using the END-IT kit (Epicentre). Then, a single ?A? base was added to 3? ends with Klenow (3??5? exo?, 0.3 U/µl). Double-stranded Solexa adaptors (75 bp with a ?T? overhang) were ligated to the fragments with DNA ligase (0.05 U/µl). Ligation products between 275 and 700 base pairs were gel purified on 2% agarose to remove unligated adaptors, and subjected to 18 PCR cycles. Completed libraries were quantified with PicoGreen (As decribed in PMID: 17603471).