Expressions of IL-6 receptor, gp130, and c-kit on cultured mast cells grown by SCF. Expressions of IL-6R, gp130, and c-kit on 10-week mast cells exposed to SCF, SCF+IL-6, or SCF+IL-4 for 2 weeks were analyzed by flow cytometry according to the procedure described in Materials and Methods. (—) Labeled with FITC-conjugated anti–IL-6R MoAb, anti-gp130 MoAb followed by FITC-conjugated GAM, or PE-conjugated anti–c-kit MoAb. (···) Labeled with FITC-conjugated mouse IgG, mouse IgG followed by FITC-conjugated GAM, or PE-conjugated mouse IgG. SCF, 100 ng/mL; IL-6, 50 ng/mL; IL-4, 20 ng/mL.