Effect of Rac1 carboxy-terminal peptide treatment of mice with chronic arthritis. (a) Delta hind paw ankle joint swelling of mice that started treatment at day 29 with 4 mg of Ctrl or Rac1 peptide (three times weekly). Values are representative of two independent experiments (n = 16 per group). (b) Area under the curve (AUC) calculated as in Figure 2b. Paraffin-embedded sections of the hind paws were stained with hematoxylin and eosin and analyzed for (c) synovial inflammation and (d) cartilage destruction. (e) X-rays were analyzed for bone damage (n = 16 per group). (f) Sera from mice that started treatment at day 29 (n = 7) with Ctrl (white bars) or Rac1 (black bars) peptide were collected, and the levels of specific anti-collagen IgG were detected. IgG levels in the sera of Ctrl-treated mice were set to 100%, and the levels obtained in the sera of Rac1 peptide-treated mice were then calculated relative to Ctrl. Represented values were calculated within linear regions of the serum dilution curve. All values are expressed as mean ± standard error of the mean. *P ≤ 0.05. Ctrl, control.