Silencing of FBXO21 in primary human CD34+ cells showed only ~50% reduction in colony-formation with no induction of early apoptosis, whereas in primary AML cells there was ~90% reduction in colony formation and up to 40% induction of early apoptosis suggesting a therapeutic window for targeting FBXO21 in the context of AML. This evidence concerns the gene CD34 and acute myeloid leukemia.