FLT3 and acute myeloid leukemia: Although FLT3-ITD mutations are present in the primitive human CD34+CD38− stem/progenitor cell compartment, including LMPP-like cells (Levis et al., 2005; Goardon et al., 2011; Mead et al., 2013), FLT3 ITDs appear to be absent in the majority of “preleukemic” HSCs in patients with FLT3-ITD AML (Jan et al., 2012).