[produced in response to specific stimuli by a variety of cell types, including neutrophils, basophils, platelets, and endothelial cells; several molecular species of platelet activating factor have been identified which vary in the length of the O-alkyl side chain; an important mediator of bronchoconstriction. ( CSP )]
UMLS (NCI) C0032172 Relation/PAR: Blood Coagulation Factor