ITGA2B and Sepsis: While no significant increase in P-selectin levels or GPIIb/IIIa activation (detected by JON/A binding) was observed in circulating platelets after 4 h, platelets from S. aureus-injected WT mice were more significantly activated by PAR4-AP stimulation than those from PBS-injected mice (Figure 2D,E), displaying a trend toward increased platelet reactivity in sepsis.