Platelet Glycoprotein Hb/HIa Complex in Cultured Cells. Localization in Focal Adhesion Sites in Spreading HEL Cells

A panel of mouse monoclonal antibodies (MoAbs) was raised that react with platelet glycoproteins (GP) llb or lila. On immunofluorescence, the MoAbs reacted with 30 % to 40 % of the human erythroleukemia (HEL) cells. When the HEL cells were induced to spread on fibronectin in the presence of 1 2-O-tetradecanoylphorbol-1 3-acetate (TPA). the MoAbs reacted with the focal adhesion sites. Only some of the GPllia MoAbs reacted with cells other than platelets, megakaryocytes, or HEL cells, and these showed focal adhesion sites in cultured human endothelial cells, fibroblasts, and epithelial cells from normal kidney tubules. G LYCOPROTEINS (GP) IIb and lIla exist in the platelet cell surface membrane as a Ca2-dependent complex that is activated upon stimulation of platelets”2 and is found also in megakaryocytes.3’4 The purified protei