BCR and chronic myelogenous leukemia, BCR-ABL1 positive: However, MYB has a longer PI3K-signaling-dependent half-life in BCR/ABL-expressing cells than in normal cells, and the presence of degradation-resistant MYB mutants in transfected CML cells conveyed resistance to imatinib-mediated apoptosis independent from the MYB expression level[127].