Fig. (3) Progression of Fas-mediated cell death in A20/2J cells. A20/2J cells (1 × 10⁶ cells/ml) were incubated without or with 100 ng/ml anti-mouse Fas mAb or 5 µg/ml F(ab’)₂ of anti-mouse IgG pAb for 4 h (A) or 20 h (B) and analyzed using flow cytometry as described under “Materials and methods.”