Inhibition of the activity of wild-type Kit and primary activating Kit mutants by motesanib. Autophosphorylation (expressed as a percentage of vehicle control) of wild-type Kit (panel A) and primary activating Kit mutants (panel B) was assessed in stably transfected Chinese hamster ovary cells treated for 2 hours with single 10-fold serial dilutions of motesanib. Representative data from 1 of 2 experiments are shown. Viability (expressed as the percentage of vehicle control) of Ba/F3 cells expressing the same primary activating Kit mutants treated for 24 hours with single 10-fold serial dilutions of motesanib was also assessed (panel C). Viability experiments were performed once (representative curves are shown).