Although genome-wide analysis of mRNA expression revealed that IFNγ strongly upregulated several key anti-apoptotic genes in imatinib-treated CML stem/progenitor cells, including MCL-1L, BCL-XL, BCL2A1, PIM1, PIM2, PARP9, PARP14, and IFI6, western blot analysis could confirm the IFNγ-induced consistent upregulation of only MCL-1L, PARP9, and PARP14. This evidence concerns the gene PARP9 and chronic myelogenous leukemia, BCR-ABL1 positive.