FIG. 7.

LY294002, a specific inhibitor of PI3-K, alleviates LMP2A-mediated cell viability and antiapoptotic effects. (A) Cell viability. LMP2A-expressing Ramos and HSC-39 cells (3 × 10⁴/100 μl) were switched to RPMI 1640 medium without FBS. Cells were preincubated for 1 h without or with LY294002 (50 μM) before incubation without or with TGF-β1 (10 ng/ml). After 24 or 48 h of incubation, cell viability was measured with an MTT assay. Results are the means and standard deviations for five experiments. (B) DNA fragmentation. Cells (10⁶/ml) were switched to RPMI 1640 medium without FBS. Cells were preincubated for 1 h without or with LY294002 (50 μM) before incubation without or with TGF-β1 (10 ng/ml). After 24 h of incubation, cell cycle analyses were performed as described in the legend to Fig. 4. PI, propidium iodide. (C) Evaluation of cleavage of PARP. Cells (10⁶/ml) were switched to RPMI 1640 medium without FBS. Cells were preincubated for 1 h without or with LY294002 (50 μM) before incubation without or with TGF-β1 (10 ng/ml). After 24 h of incubation, PARP cleavage was analyzed as described in the legend to Fig. 5. Control cells were not treated with various agents. The amount of protein loaded in each lane was assessed by rehybridization of the filter with a specific antibody for human glyceraldehyde-3-phosphate dehydrogenase (GAPDH).