Imatinib mesylate (IM) treatment decreased the expression of ZFX in K562 cells and CML CD34+ cells in a dose-dependent manner (Additional file 1: Fig. S1E–F), suggesting that BCR/ABL maintained ZFX expression and ZFX played a role in the IM response of BCR/ABL+ cells. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.