Differing adhesion of human CD34⁺ cells to P- and E-selectin in the presence of function-blocking antibody to PSGL-1 or the proteases O-sialoglycoprotein endopeptidase, neutrophil elastase, and cathepsin G. CD34⁺ HPCs were preincubated with either isotype control mAb, KPL1 mAb, O-sialoglycoprotein endopeptidase (OSG), or a combination of neutrophil elastase and cathepsin G (NE+CG) and added to microwells coated with 10 μg/mL BSA, P-selectin (1800 sites/μm²), or E-selectin (550 sites/μm²). Results are expressed as mean ± SD of one representative experiment from 3 made in triplicate. *indicates statistically different (P < .05) from isotype-treated control groups.