Previous reports12,13 demonstrated that exogenously added IFNγ exert strong anti-apoptotic effect on CML cell lines and PBMCs of CML patients, but did not analyze its anti-apoptotic effect on CML stem/progenitor cells, the cell population responsible for residual disease.1,2 Our results now revealed that exogenously added IFNγ markedly counteracts imatinib-induced apoptosis of CML stem/progenitor cells. Here, IFNG is linked to chronic myelogenous leukemia, BCR-ABL1 positive.