FLT3 and acute myeloid leukemia: Compared to the CD44v6 negative K562 cells, AML cell lines with FLT3 mutation (MOLM‐13 and MV4‐11) or FLT3 overexpression (THP‐1), which expressed higher level of CD44v6, were significantly lysed by the CD44v6 CAR‐T.