Ikaros regulates transcription of genes that control cell cycle. (A-B) qChIP analysis of Ikaros occupancy of target genes that control cell cycle progression identified by ChIP-Seq in (A) Nalm6 B-ALL cells and (B) primary B-ALL cells (representative data from 1 of 4 patients without IKZF1 deletion is shown). (C) Expression of Ikaros target genes that control cell cycle progression in Nalm6 cells transduced with vector containing Ikaros compared with empty vector controls (measured by qRT-PCR). (D) Promoter activity of Ikaros target genes that control cell cycle progression measured by luciferase assay following transfection with Ikaros or control vector. (E) Effect of Ikaros knockdown on the gene expression of Ikaros targets that control cell cycle progression. Gene expression is determined by qRT-PCR using total RNA isolated from Nalm6 cells transfected with scramble shRNA or Ikaros shRNA and cultured for 2 days. (F) Effect of Ikaros knockdown on cell cycle gene expression. Nalm6 cells were transduced with lentivirus containing Ikaros or empty vector then cell cycle analysis was performed by flow cytometry. (G) Quantification of cell cycle data. (H) Model of Ikaros-mediated regulation of cell cycle progression: Ikaros represses transcription of genes that promote cell cycle progression at different stages of the cell cycle, leading to negative regulation of cell cycle progression.