P-selectin belongs to a family of divalent cation dependent carbohydrate-binding glycoproteins or adhesion molecules. P-selectin is expressed transiently on the surface of activated platelets and endothelial cells. Secreted P-selectin is thought to play a key role in the adhesion of platelets to monocytes and neutrophils during an inflammatory response. Levels of P-selectin may be elevated in a number of pathological conditions. Recombinant human P-selectin comprises a 566 amino acid fragment (197-761) corresponding to the cysteine rich complement control protein domain and is expressed in E. coli with an amino-terminal hexahistidine tag.