Differential sensitivity of Val560Gly and Asp816Val mutant KIT in HMC1 subclones to KIT inhibitors.

Antiphosphotyrosine blots of immunoprecipitated KIT expressed in 2 HMC1 subclones show that spontaneous phosphorylation of KIT containing only the juxtamembrane RT Val560Gly mutation in the HMC1.1 clone is susceptible to inhibition by both inhibitors at 0.1 to 1 μM (lanes 1-3). In contrast, spontaneous phosphorylation of KIT with both the Val560Gly and the EST Asp816Val mutation in the HMC1.2 clone is resistant to both inhibitors at 1 to 10 μM (lanes 4-6).