SHP2 is essential for oncogenic KITD814V-induced ligand-independent survival. (A) Primary BM-derived WT KIT or KITD814V-expressing cells were starved and treated with indicated concentrations of II-B08 for 48 hours. Assays were performed in the presence of SCF (50 ng/mL) for cells bearing WT KIT and in the absence of growth factors for cells bearing KITD814V. Cells were harvested and stained with PE-conjugated anti–annexin V antibody and 7-amino-actinomycin D followed by flow cytometric analysis. Left panel: representative flow micrographs. Right panel: bars represent the mean percent of surviving cells from 2 independent experiments. *P < .05. (B) Primary BM cells bearing WT KIT or KITD814V from WT or SHP2^−/− mice were starved of serum and growth factors for 6 hours and cultured in media containing serum for 48 hours in the absence of growth factors. After 48 hours, cells were harvested and stained with PE-conjugated anti–annexin V antibody and 7-amino-actinomycin D followed by flow cytometric analysis. Left panel: representative flow micrographs. Right panel: bars represent the mean percent of surviving cells from 1 of 3 independent experiments. *P < .01.