Validation of Ikaros targets in primary megakaryocytes. (A) Fold changes in expression of the selected Ikaros target genes in megakaryocytic cultures of bone marrow cells. IK1- or IK7-transduced whole bone marrow cells were GFP sorted at 48 hours and cultured under megakaryocytic conditions (SCF/THPO) for 3 days prior to RNA extraction. Genes bound by IK1 are in bold (defined as having >0, but <30 tags), and genes that are stringently bound (defined as having >30 tags) are bold and underlined. Means ± SD from 4 independent experiments are shown. *P ≤ .05; #P ≤ .01; $P ≤ .001. (B) Fold changes in expression of selected megakaryocytic genes in CD41-positive sorted cells isolated from 8- to 9-week-old wild-type, Ikaros^+/−, and Ikaros-null mice. Means ± SD from 3 independent experiments are shown. *P ≤ .02 relative to Ik^+/−.