Figure 4.

Cell culture angiogenic activity secreted by fibrosarcoma cells . (A) Medium collected from cultured fibrosarcoma cells (FS) was untreated or was incubated with mAb 209 (specific for PLF) or 28.1.1 (nonspecific control). Ab-antigen complexes were removed by using protein G beads. After these treatments, the medium was analyzed by gel electrophoresis and immunoblotting for the removal of PLF protein. Medium from cultured mouse placentas isolated on day 13 of gestation was used as a positive control for PLF detection; Ponceau-S staining shows equal protein loading (Left). (B) Basal endothelial cell migration was measured in a Boyden chamber in the presence of 0.1% BSA, and maximally induced migration was determined after addition of 10 ng/ml of bFGF. Fibrosarcoma culture medium, either intact or after removal of PLF, was also tested. Each sample was also assayed after addition of a neutralizing Ab against bFGF. Results were analyzed by a one-way ANOVA followed by a Tukey's post hoc test. n = 4, and the results were reproduced with an independently generated set of samples. a vs. b, c, or d: P < 0.001; c vs. d: P < 0.01; c vs. e: P < 0.001; d vs. f: P < 0.001.