FIGURE 4.

Geldanamycin prevents cell-surface processing of Pro-Cat by furin. A, monensin treatment was used to block protein trafficking. After cell-surface biotinylation, biotinylated ADAMTS9 Pro-Cat was chased in conditioned medium in the continuing presence of monensin (50 μg/ml) alone or in the presence of monensin (50 μg/ml) plus geldanamycin (GA) (10 μm). Western blotting was done with anti-Myc. Note that in the absence of geldanamycin, an increased amount of processed catalytic domain (C) is observed in the conditioned medium (left-hand panel). B, in the absence of geldanamycin, the zymogen (Z) declines more rapidly in the cell lysates (right-hand panel). Lower panels in A and B represent the mean and S.D. of three independent experiments. The statistical significance is shown.