IFNA1 and chronic myelogenous leukemia, BCR-ABL1 positive: Figure 5B also shows that the proliferation indices for the naïve, effector and central memory PR1-CTL were approximately 2.5 whereas the proliferation index for the terminally differentiated PR1-CTL was 4.4. Senescent T cells have been shown to express CD57 [33] and PR1-CTL from IFN-sensitive CML patients off all therapy do not express CD57 (data not shown), indicating that PR1-CTL with a terminally differentiated phenotype are not senescent.