Analysis of Rap1a, knockout/wild-type ratios (KO/WT) of proliferation responses and IL-2 production to CD3, CD3/CD28, and TPA/ionomycin stimuli in T cells. The asterisks above the error bars indicate the significance of the results: ✽✽✽, P < 0.001; ✽✽, P < 0.01). (A) Relative proliferation changes in T cells. The estimated KO/WT proliferation ratios lie at 0.78 for CD3 and at 0.9 for CD3/CD28. (B) Relative IL-2 production in Rap1A−/− T cells measured 48 h after stimulation. The estimated KO/WT IL-2 production ratios lie at 0.28 for CD3 and at 0.81 for CD3/CD28.