Induction of tyrosine phosphorylation of cellular proteins by thrombin and thrombin receptor agonist peptide in different Jurkat cell clones. Cells were stimulated for the indicated times with 100 nmol/L thrombin (A) or 2.5 μmol/L thrombin receptor agonist peptide (B). Proteins from cell lysates were separated by SDS-PAGE and transferred to Immobilon membranes for Western blotting with biotin-conjugated 4G10 antibody. Blots were further incubated with horseradish peroxidase-conjugated secondary antibody and immunoreactivity was detected by enhanced chemiluminescence.