Fas ligation blocks cell death and enhances expression of proinflammatory cytokines. Fas-induced cell death of NIH3T3 fibroblasts (n = 3) measured by fluorescence-activated cell sorting (a) and the relative expression of tumor necrosis factor (TNF)-α (b) and IL-6 (c) mRNA in NIH3T3 fibroblasts (n = 3), determined by real-time PCR. Cells (1 × 106/ml) were stimulated with 50 ng anti-Fas antibody/ml or 50 ng anti-Fas antibody/ml and 1 μg protein G for 24 hours. Control cells were incubated with medium only. AB, antibody.