Western blot analysis on tyrosine phosphorylation of FLT3 and STAT5 in leukemia cell lines with or without D835 mutations. Lysates of leukemia cell lines with (lanes 1-2) or without (lanes 3-5) FLT3-D835 mutations were separated, blotted, and stained with antibodies against FLT3, phosphotyrosine (after immunoprecipitation by anti-FLT3), STAT5, phospho-STAT5, and α-tubulin, respectively. Lanes 1, 3, and 4 were B-precursor cell lines with MLL rearrangement; lane 2 was a monocytoid cell line with MLL rearrangement; lane 5 was a T-lymphoid cell line.