Plasma MMP9 levels during HPC mobilization. (A) Plasma was collected from wild-type mice at baseline (control), 15 minutes after IL-8 administration (30 μg, intraperitoneal; IL-8), or 5 days after treatment with G-CSF (250 μg/kg per day for 5 days; G-CSF). As a control, MMP-9–deficient mice treated with G-CSF also were analyzed. (B) Plasma was collected from wild-type mice after IL-8 administration or from G-CSFR–deficient mice at baseline or after IL-8 administration. (C) Plasma was collected from wild-type mice at baseline, after IL-8 administration, or 8 days after treatment with cyclophosphamide (200 mg/kg; CY). In each case, equal amounts of plasma proteins were analyzed by gelatin zymography. Results are representative of 3 independent experiments. Molecular size markers are indicated at left in kDa.