CD47 and leukemia: In 2009, Majeti et al. first reported that CD47 was a biomarker of poor prognosis in patients with acute myeloid leukemia (AML); in their superb publication, authors demonstrated that CD47 was more highly expressed on AML leukemia stem cells than their normal counterparts, and that increased CD47 expression predicted worse overall survival in three independent cohorts of adult AML patients [24].