The Selectin family is comprised of three members, E-Selectin, L-Selectin, and P-Selectin. E-Selectin [endothelial leukocyte adhesion molecule-1 (ELAM-1), CD62E] is transiently expressed on vascular endothelial cells in response to IL-1 beta and TNF-alpha. The human and rat proteins share approximately 67% amino acid sequence identity. The mouse and rat proteins share approximately 78% amino acid sequence identity. L-Selectin (Leukocyte Selectin, LAM-1, LECAM-1, LECCAM-1, TQ1, Leu-8, MEL-14 antigen, DREG, lymph node homing receptor, CD62L) is expressed constitutively on a wide variety of leukocytes. Two forms of L-Selectin have been reported, apparently arising as a result of post-translational modifications. Human and mouse L-Selectin share 76% amino acid sequence identity. Human P-Selectin (GMP-140, LECAM-3, PADGEM, CD62P) is expressed by activated platelets and endothelial cells. The extracellular domains of human and mouse P-Selectin share approximately 73% amino acid sequence identity.