Fas expression and the induction of apoptosis is shown. Δ-apoptosis (Δ200 and Δ1000; % increase of apoptosis after the incubation with anti-Fas MoAb at different concentration) is the percentage of increased number of apoptotic cells by colorimetric DNA fragmentaion assay. (▪ and • indicate the value after the culture with anti-Fas at the concentration of 200 and 1,000ng/mL, respectively.