p-selectin is also very important in the recruitment and aggregation of platelets at areas of vascular injury. in a quiescent platelet, p-selectin is located on the inner wall of α-granules. platelet activation (through agonists such as thrombin, type ii collagen and adp) results in "membrane flipping" where the platelet releases α- and dense granules and the inner walls of the granules are exposed on the outside of the cell. the p-selectin then promotes platelet aggregation through platelet-fibrin and platelet-platelet binding.