FLT3 and acute myeloid leukemia: Pim kinase inhibitors have little single-agent activity in AML in vitro [8, 9, 13, 34] or clinically [10], but potently enhance the activity FLT3 inhibitors [8, 9, 34] and topoisomerase 2 inhibitors [13] in AML with FLT3-ITD, and may also enhance the activity of other signal transduction inhibitors and cytotoxic chemotherapeutic agents in other AML subtypes and other hematologic malignancies [12].