FLT3 and acute myeloid leukemia: Htra3 inhibited apoptosis, specifically promoted the proliferation of multipotent hematopoietic progenitors bearing FLT3-ITD in vivo, and enhanced the inhibition of differentiation by Lin28a. The upregulation of Htra3 and the downregulation of Lin28a, combined with the presence of ITD/ITD, induced AML with similar morphology as leukemic cells from double-transgenic mice.