The inhibitory effect of imatinib mesylate on DC differentiation is not mediated by c-Kit. Mobilized human CD34⁺ PBPCs were cultured in the presence of GM-CSF, TNF-α, IL-4, and FLT3L with or without blocking antibodies against SCF (anti-SCF) and c-Kit (anti–c-Kit). Mouse IgG was added to control cells. DC surface marker expression was measured by FACS analyses. The surface expression is indicated as mean fluorescence intensity. Shaded histograms represent the isotype control; open histograms, the indicated antibody.