CD34 and chronic myelogenous leukemia, BCR-ABL1 positive: Although co-culture with MSCs partially protected leukemic cells from nutlin3a-induced cell death, nutlin3a was still able to induce apoptosis in both proliferating (EC50 = 10.9 ± 3.7 μM) and quiescent (EC50 = 34.2 ± 3.7 μM) CD34+ CML cells (Figure 3).