Time response of KIT substrate molecules AKT and STAT3 to 17-AAG in HMC-1.1 and HMC-1.2 cells. Mast cells were incubated for increasing time intervals with 1 μM 17-AAG and levels of AKT (A,B), phosphorylated AKT (C,D), STAT3 (E,F), phospho-STAT3 (G,H), and tubulin (I,J) were measured as described in “Patients, materials, and methods.” Tubulin protein was measured to confirm that equal amounts of protein were added to each lane.