PKC412 down-regulates growth of primary neoplastic (mast) cells exhibiting D816V. Primary neoplastic BM cells exhibiting KIT D816V were isolated from a patient with SSM. Isolated cells were incubated in control medium (Co) or with various concentrations of PKC412 or imatinib (1 μM) as indicated. Cell growth was quantified by measuring ³H-thymidine uptake. Results are expressed as percent of control (Co, 100%) and represent the mean ± SD of triplicates. In normal BM cells, no effects of PKC412 were seen (not shown).