Analysis of primary bone marrow cells obtained from patients with mastocytosis. (A) HinfI restriction analysis of bone marrow cells isolated from patients with systemic mastocytosis. RNA was isolated from either unselected bone marrow or CD25-sorted marrow cells. The presence of the KIT^D816V mutation is indicated by the appearance of a novel restriction fragment as indicated by the arrow. (B) Primary neoplastic mast-cell viability following culture of bone marrow isolated from 4 patients with systemic mastocytosis in the presence of imatinib or dasatinib. Bars indicate mean ± SEM from duplicate cultures for each dose in 4 different patients. P < .001 comparing no treatment with 0.1 and 1 μM dasatinib by 2-tailed t test on pooled data.