Inhibitory effect of IMD-0354 on proliferation of neoplastic mast cells. HMC-1 cells were incubated in the presence of increasing concentrations of IMD-0354 (A), STI571 (B), and PDTC (C) for 24, 48, and 72 hours, and the numbers and viability of cells were determined by a dye exclusion test and an MTT assay. Each point represents the mean ± SE of 6 different experiments. (D) IC-2^WT cells, IC-2^G559 cells, and IC-2^V814 cells were incubated with various concentrations of IMD-0354 or STI571 in the presence (IC-2^WT) or the absence (IC-2^G559 and IC-2^V814) of 100 ng/mL SCF. After 48 hours, proliferative activity of these cells was evaluated through MTT assay. Data represent the mean ± SE of 6 different experiments.