FIGURE 6.
The effect of PD98059 and hyperosmotic stress upon nucleolin mobilization and cellular levels of PP-InsP5 and [PP]2-InsP4. U2-OS cells were treated with either vehicle or PD98059 (50 μm for 30 min) followed 30 min later by either vehicle or sorbitol (200 mm for 30 min). Then, cells were fixed and stained for nucleolin (red signal) as described under “Experimental Procedures.” Nucleolin distribution was determined by confocal microscopy. A, representative images. In parallel, the levels of PP-InsP5 and [PP]2-InsP4 in [3H]inositol-labeled cells was determined by HPLC (B and C). D, mean (±S.E.) values for nucleolin intensity in the nucleoplasm from 11-16 cells for each condition.