Events in the gap. The gap between activated platelets in a growing thrombus is small enough for integrins and other cell adhesion molecules (CAMs) to interact and for interactions to occur between receptors such as Eph kinases and their cell surface ligands, known as ephrins. The space between platelets also provides a protected environment in which soluble agonists (ADP and TxA₂) and the proteolytically shed exodomains of platelet surface proteins can accumulate. Signaling by ephrins and Eph kinases promotes integrin engagement and outside-in signaling. The mechanical forces generated by the contraction of actin/myosin filaments may compress the space between platelets, improving contacts and increasing the concentration of soluble agonists. The binding of cell adhesion molecules to their partners may limit diffusion into and out of the space between platelets in addition to stabilizing platelet/platelet interactions.