The effect of the A2 protein on the fibrin clot structure. (A) Confocal microscopy images of fibrin clots at a magnification of ×200 formed in plasma from healthy human donors. Note that the effect of the A2 protein (0.25 μM) on the resultant clot structure (right) is evident as compared with plasma incubated with vehicle control (left). Scale bars, 10 μM. (B) The WT A2 protein clearly altered the resultant fibrin structure as compared with plasma treated with vehicle control and the A2 mutant. Scale bars, 50 μM.