Comparison between the BCR-ABL/ABL ×100 ratios of the patients who expressed the Ik1, Ik2 DNA-binding isoforms alone and patients expressing the Ik6 dominant-negative isoform alone, independent of the clinical disease status. (A)There was a strong correlation between Ik6 expression and BCR-ABL transcript levels (P < .001). Expression pattern of Ikaros isoforms at different checkpoints during treatment with tyrosine kinase inhibitor: at diagnosis (B), during remission (C), and at the time of relapse (D) (both hematologic/cytogenetic and molecular). In patients with relapse and high levels of BCR-ABL transcript, Ik6 was the major isoform expressed. (E) RT-PCR analysis at baseline (lane 1), during remission (lane 2), and at the time of relapse (lane 3).