Antiapoptotic gene XIAP is highly expressed in CD34⁺ CML relapse cells from Pt1 compared with CML and AML cells from other patients. Expression of apoptosis-regulating genes was determined by real-time quantitative RT-PCR in CML cells from Pt1 obtained at relapse 1 and relapse 2, and a panel of CML and AML samples. Expression is depicted as ΔΔCt values and was quantified relative to AML cell line KG1, which was set at 1 ΔΔCt, and normalized for the expression of housekeeping gene HMBS.