ZFN-L/R and donor DNA significantly suppressed the proliferation and promoted the apoptosis of CD34+ cells from CML patients (Fig. 5b-f), but had no effect on CD34+ cells from bcr-abl negative patients who suffered from anemia (Additional file 6: Figure S6A-D). This evidence concerns the gene CD34 and chronic myelogenous leukemia, BCR-ABL1 positive.