ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: The story of imatinib (Glivec) began with the recognition by Janet Rowley in 1973 that the CML-associated 22q- Philadelphia Chromosome (Ph1) [2] was in fact a translocation product with a reciprocal 9q+ chromosome [3] A decade later it became understood that most patients had a 22q-breakpoint within a defined 5.8 kb region that became known as the ‘breakpoint cluster region’ bcr and that the 9q component of the translocations involved the proto-oncogene c-abl.