Cells were cross-linked with formaldehyde and nuclear DNA was sonicated with 200-300bp, then the H3K4me1-DNA complexes were isolated with antibody. ChIP DNA libraries were made following Illumina ChIP-Seq library preparation kit and subjected to Solexa sequencing (Illumina) at the CCR-Sequencing Facility, National Cancer Institute. Sequencing was performed on Illumina Genome Analyzer IIx.