Fig. 7. Effect of the PI 3-kinase inhibitors wortmannin and LY294002 on the thapsigargin-stimulated transport of ricin to the Golgi apparatus. MDCK II cells were incubated with radioactive sulfate for 3 hours at 37°C, and after 2 hours increasing concentrations of wortmannin (A) or LY294002 (B) were added to the medium. During the last 30 minutes the cells were incubated in the presence of 0.1 µg/ml thapsigargin. Then ricin sulf-2 (200 ng/ml) was added, and the incubation was continued for 2 hours. The cells were further treated as described in the legend to Fig. 3. Because of the instability of wortmannin, equal amounts were added every 45 minutes during the incubation time (3 hours) so that the final concentrations were 100 nM, 1 µM or 10 µM.

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