Flow cytometric determination of HS. HUVECs treated with staurosporine (left panels) or kept in suspension with serum deprivation (right panels) for 2, 4, and 8 hours were harvested, washed, and incubated with ATIII for 30 minutes. Cells were then stained with an antihuman ATIII MoAb, followed by an FITC-conjugated goat antimouse antibody. The M1-region is defined as the percentage of events below the control (all panels, right peak). The results of one representative experiment of three performed are shown.