To further analyze the mechanisms of PTK inhibitor resistance, we asked whether structurally different length mutations in the JM region can lead to the differences in the sensitivity to the FLT3 PTK inhibitor SU5614 in the background of the FLT3-D835N construct...We found that all these dual mutants show partial resistance to SU5614 although to a different degree (IC50 = 0.3 μM for the V592A-D835N and 1 μM for the NPOS-D835N mutant) (data not shown).