SU5614 inhibits the tyrosine phosphorylation of FLT3, STAT3, and STAT5, and down-regulates STAT5 target genes in a dose-dependent manner.
(A) MM6 cells expressing a constitutive active FLT3 were incubated for 3 hours with the indicated concentrations of SU5614, and protein lysates were immunoprecipitated (IP) with FLT3 antibody. Precipitates were subjected to SDS-PAGE and after blotting, membranes were incubated with αPY antibody. Blots were stripped and probed with αFLT3 antibody. (B) MM6 cells were incubated for 3 hours with SU5614. Protein lysates were subjected to SDS-PAGE and after blotting, membranes were probed with phospho-specific antibodies against STAT3 and STAT5 followed by reblotting with specific STAT3 and STAT5 antibodies. (C) Ba/F3 cells expressing the FLT3ITD NPOS mutant were incubated for up to 72 hours with the indicated concentrations of SU5614. Protein lysates were analyzed by SDS-PAGE as described in panel B and blots were probed with antibodies against BCL-XL, p21, and β-actin.
