The antitumor activity of 2B6 in B-lymphoma xenografts requires a functional Fc. Daudi cells (5 × 10⁶/mouse) were suspended in Matrigel and injected subcutaneously into the right flank of 7-week-old BALB/c nude female mice (N = number of mice per group). Intraperitoneal injections of antibodies (250 μg/mouse): ch2B6 (□), ch2B6-N297Q (•), rituximab (♦), or PBS (○), were performed weekly for 8 weeks, starting at day 0. Mean tumor volumes are plotted and error bars represent the SE of measurement.