FLT3 is expressed in normal hematopoietic progenitor cells, in most acute myeloid leukemia's (AML), and a smaller subset of B-cell acute lymphoblastic leukemia (ALL), blast crisis chronic myeloid leukemia (CML) and T-cell ALL [2]. This evidence concerns the gene FLT3 and chronic myelogenous leukemia, BCR-ABL1 positive.