Integrin alpha IIb beta 3 exist in a conformational equilibrium clustered around four main states. These conformations range from a compact bent nodule to two partially extended intermediate conformers and finally to a fully upright state. Activation of blood platelets by physiological stimuli at sites of vascular injury induces inside-out signaling, resulting in a conformational change of the prototype Integrin alpha IIb beta 3 from an inactive to an active state competent to bind soluble fibrinogen. Furthermore, ligand occupancy of Integrin alpha IIb beta 3 outside-in signaling and additional conformational changes of the receptor, leading to the exposure of extracellular neoepitopes termed ligand-induced binding sites (LIBS), which are recognized by anti-LIBS monoclonal antibodies.