Fluorescent microscopy of PAR-1 on HEL cells.

Cells were stained with the cleavage-sensitive PAR-1 antibody SPAN 12 (A and C) or the cleavage-insensitive PAR-1 antibody WEDE 15 (B and D) and treated with no agonist (A and B) or Sk (C and D) in plasma from an individual whose platelets aggregated to Sk.