BCR and chronic myelogenous leukemia, BCR-ABL1 positive: An initial review of CML-derived cell lines indicated early support for the hypothesis that the Ph translocation is not restricted to lineage-committed progenitor cells [5], and ABL-specific TKIs are consistently effective against human CML and Ph+ cell lines in vitro because of their dependence on BCR-ABL for proliferation and survival 6, 7.