Down-regulation of mutant Kit–dependent signaling by AP23464. Cell-lysate immunoblots for (A) phospho-Akt-serine 473 and (B) phospho-STAT3-tyrosine 703 were performed for D816V Ba/F3, P815 m-D814Y, the juxtamembrane mutant HMC-1, and SCF-stimulated Mo7e cell lines following treatment with escalating AP23464 concentrations. SCF stimulation of Mo7e cells did not induce STAT3 tyrosine phosphorylation and thus is not shown. Simultaneous total Akt and total STAT3 blots were done as loading controls. Representative gels are shown.