In the 1990s, John E. Dick and Dominique Bonnet, researchers at the University of Toronto, in Toronto, Ontario, investigated how a blood cancer called acute myeloid leukemia, or AML, arises from blood-forming cells. Researchers in the field at the time did not know which cells initiate and maintain AML in the body, and there were conflicting hypotheses about which cells were responsible. Scientists hypothesized that AML might be mainly composed of more specialized and differentiated blood cells. Dick and Bonnet conducted experiments in which they grew human AML cells in mice and investigated which cells initiated and maintained the cancer to explore that hypothesis. Their study was one of the first to use sensitive mouse models to characterize and uncover which cells initiated and comprised AML, which contributed to the understanding of its cellular origin and aided in the development of targeted therapies for leukemia treatment.