Chronic Myelogenous Leukemia (CML) is a type of cancer that is caused by a specific chromosomal alteration that leads to the inappropriate expression of a kinase called Abl. Kinases are enzymes that put phosphate groups onto macromolecules such as proteins. A drug used to treat CML, imatinib, binds to the active site of Abl kinase. Why does this drug work to treat this type of cancer