CD9 and acute myeloid leukemia: Potentially contradictory to our finding, others report elevated CD9 expression in AMLs with NPM1 mutation, as compared to AML cases that were NPM1 wild type.9,15 Although we did find that CD9 expression was overall higher in AML with the NMP1 mutation compared to some AML subtypes and normal myeloid blasts, it was not across all AML subtypes (Figure 4, Table 1).