Effect of Rac1 carboxy-terminal peptide treatment on T-cell costimulatory protein expression. Splenocytes from mice primed with bovine collagen type II in complete Freund's adjuvant analyzed in Figure 7 (n = 6) were examined for ICOS and CD154 expression by fluorescence-activated cell sorting analysis following 24-hour stimulation with anti-CD3 and anti-CD28 antibodies in the presence of Ctrl or Rac1 peptide (200 μg/mL). The percentages of CD3+CD4+ T cells expressing CD154 and ICOS (a) and the mean geometric (geomean) fluorescence intensity (mfi) of CD154 and ICOS expression on these cells (b) were calculated following fluorescence-activated cell sorting analysis. Data points within each column represent values obtained from splenocytes of individual mice, and the bar indicates the median value. *P ≤ 0.05; **P < 0.01. Ctrl, control.