Ikaros binds and represses critical megakaryocytic genes. (A) Heatmap of the 4325 genes differentially expressed in 6133 cells overexpressing IK1. Selected genes of interest are shown. (B) Venn diagram of the overlap between bound and differentially expressed genes in 6133 cells overexpressing Ikaros. (C) Pie chart of the location of peaks relative to the 309 differentially expressed genes that are bound by Ikaros. Promoters are considered to be 2 kb upstream of the TSS. (D) De novo motif finding using 200 bp of sequence surrounding the peak center of the Ikaros peaks. A database of known transcription factor binding motifs was interrogated to find the closest match for each motif. The score indicates the similarity between the found motif and the motif in the database with 1 being a perfect match. (E) UCSC Genome Browser depiction of Ikaros chromatin occupancy in 6133 cells at selected megakaryocyte genes. (F) Western blot of Ikaros and GATA-1 expression in 6133 cells transduced with IK1, IK7, or GFP alone. HSC70 is included as a loading control. Quantification of band intensities relative to Hsc70 and normalized on protein extracted from cells transduced with the empty retroviral vector Migr1 are indicated (also see supplemental Figure 2B).