CREB1 and acute myeloid leukemia: Induction of FST expression by FLT3/ITD could be recapitulated in adult FLT3/ITD‐transgenic zebrafish, Flt3/ITD knock‐in mice, and human FLT3/ITD primary AML‐derived murine xenografts, which was mediated by CREB phosphorylation.