Thrombin receptor expression in different Jurkat cell clones. Cells were first stained with the antihuman thrombin receptor ATAP2 MoAb (black area) or an isotype matched control antibody (white area), followed by biotinylated goat antimouse antibody and phycoerythrin-streptavidin. Stained cells were analyzed with a flow cytometer FACScan (Becton Dickinson) gated to eliminate nonviable cells.