SU11652 is a potent FLT3 inhibitor. A. Tyrosine kinase activity of recombinant FLT3, FLT3D835H, and FLT3 D835Y was analyzed with GST-FLT3S as the substrate in the presence of various concentrations of SU11652. Tyrosine phosphorylation of GST-FLT3S was detected by using anti-phosphotyrosine antibody PY20, and its protein level, by Coomassie blue staining. B. The relative kinase activity was calculated based on the density of the western blot bands normalized to the control group. Error bars denote standard deviation (n = 3).