ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: The parental cells, derived from a chronic myeloid leukemia patient [33], are useful for studying apoptosis because they harbor a well-defined immortalizing BCR-ABL fusion [34], have easily manipulatable nearly-haploid (HAP1) or fully-haploid (eHAP) genomes [33,35], and are p53-proficient [36].