Moreover the finding that 12 AML cell lines studied (which are usually established from more “aggressive” types of leukaemia with autonomous in vitro growth) do not regulate FLT3, further suggest that the non-regulating phenotype is not physiological, and that some AML blasts lose the property of a physiological, hypoxia-mediated FLT3 regulation. This evidence concerns the gene FLT3 and leukemia.