Wild-type and codon 816 mutated KIT protein are degraded and inactivated in transiently transfected Cos-7 cells. Cos-7 cells were transiently transfected with vectors coding for either wild-type or Asp816Val mutated KIT protein and then exposed to 1 μM 17-AAG for increasing lengths of time. Levels of KIT protein (A-B) and phosphorylated KIT protein (C-D) were measured as described in “Patients, materials, and methods.”