MLL target genes in Fusion/Fusion cells are a subset of that in Fusion/WT or WT/WT cells. (A) Detection of MLL binding using ChIP-chip at the MEIS1 locus. Cross-linked chromatin from ML-2, U937, THP-1 cells was immunoprecipitated with the MLL antisera separately. The Ab precipitated DNA and the input DNA were labeled with Cy5 and Cy3, respectively, and hybridized to a customized NimbleGen array containing the entire gene loci of 144 genes (see “Analysis of ChIP-chip data”). The level of MLL protein enrichment is shown as Log2(ChIP/input). The promoter and 5′ gene region of MEIS1 is boxed by a dotted line, and the 3′ gene region is boxed by solid line. (B) The genomic loci of 144 human genes were examined for enrichment of MLL protein binding using the customized NimbleGen array. MLL target genes identified in ML-2 (Fusion/Fusion), THP-1(Fusion/WT), and U937 (WT/WT) cells were compared.