Factor-independent proliferation of MIHCs expressing D816V c-Kit is more sensitive to a PI3K inhibitor than SCF-induced proliferation of cells expressing wild-type c-Kit.

Cells were incubated for 4 hours at the indicated concentration of wortmannin and then cultured for 72 hours in growth media alone (MIHC-D816V) or supplemented with 100 ng/mL huSCF, as indicated (MIHC-Kit). Samples were pulsed with ³H-thymidine and harvested 4 hours later as described in “Materials and methods.” Mean percentage control and standard deviation were calculated using the ³H-thymidine incorporation of triplicate samples in the presence and absence of wortmannin. These data are representative of the results of 4 independent experiments.