Figure 9.

Involvement of MEK in the YC-1-induced increase of COX activity and COX-2 expression in A549 cells. In (a), cells were pretreated with various concentrations of PD (MEK inhibitor) for 30 min, and then incubated with YC-1 (50 μM) for 12 h. The media were then removed, and the COX activity was measured by examining the PGE₂ formation in the presence of 30 μM exogenous arachidonic acid for 30 min. Results are expressed as means±s.e.mean of three independent experiments performed in duplicate. ^*P<0.05 as compared with treatment with YC-1 alone. In (b), the cells were pretreated with PD (10 and 30 μM) for 30 min and then incubated with YC-1 (50 μM) for 12 h. Immunodetection using anti-COX-2 or α-tubulin specific antibody was performed as described in Methods. The equal loading in each lane was demonstrated by the similar intensities of α-tubulin. Data are representative of three independent experiments, which gave essentially identical results. PD, PD98059.