IK and leukemia: In order to evaluate IK function in BPL cells, we examined in patient-derived leukemia cells (i) transcript expression levels of IK target genes and IK-regulated lymphoid priming genes, (ii) protein expression levels of IK in whole cell lysates and nuclear protein extracts, (iii) subcellular localization of IK (nuclear localization requires DNA binding function of IK), and (iv) DNA binding activity of native IK.