For that we used four human cell lines: K562—chronic myeloid leukemia cell line; MV4;11—acute myeloid leukemia cell line, bearing mutant FLT3; U937 cells, widely used as a model for monocytic leukemia study; THP-1—acute monocytic leukemia cells. This evidence concerns the gene FLT3 and chronic myelogenous leukemia, BCR-ABL1 positive.