Chondroitinase ABC pretreatment of CD34⁺ cells blocks bPF4 binding. Y-axis, CD34–phycoerythrin (CD34-PE) binding; x-axis, streptavidin-FITC (SA-FITC)/bPF4 binding. (A) Negative control. No chondroitinase, no bPF4 exposure, labeling with SA-FITC and irrelevant IgG-PE. (B) Positive control. No chondroitinase, bPF4 at 10 μg/mL, labeled with CD34-PE and SA-FITC. (C) Cells exposed 2 hours to 200 mU/mL chondroitinase ABC, then labeled as for panel B. (D) As in panel C, but with 4 hours exposure to chondroitinase ABC. The percent of CD34⁺ cells labeling positive for PF4 is shown in the upper right of each panel