SDF-1 induces MMP-9 expression of AdCXCR4-infected megakaryocytic leukemic cells.

(A) HEL cells, which normally posses low CXCR4 levels, were infected with AdNull and AdCXCR4 adenoviral vectors. After overnight infection, cells were washed 3 times and analyzed for their CXCR4 surface expression. (B) Cells were cultured in the presence of rhSDF-1 (200 ng/mL per day) for 48 hours, and supernatant proteolytic activity was analyzed by gelatinolytic zymography. (C) Gelatinolytic activity was quantified by densitometry. Stimulation of the AdCXCR4-infected cells with SDF-1 resulted in a 100% increase in pro–MMP-9 (92 kd) compared with similarly treated AdNull-infected cells. Results are representative of 3 separate experiments.