SCUBE-1 is a newly identified, secreted cell surface protein that is determined during early embryogenesis. This protein consists of cascading EGF-like repeats following the N-terminal signal peptide sequence, a spacer region, cysteine-rich repeat motifs, and a CUB domain at the C-terminus. These molecules are stored in alpha granules in inactivated platelets, translocated to the platelet surface after activation by thrombin, secreted as small soluble fragments, and incorporated into the thrombus.