FIG. 1.

Apigenin inhibits UVB-induced COX-2 expression and subsequent PGE₂ production. 308 mouse keratinocytes were grown to 90% confluence and irradiated with UVB; control cells were sham irradiated. (A) Western blot analysis showing dose-dependent induction of COX-2 protein at 8 h postirradiation. (B) Time-dependent induction of COX-2 protein expression by UVB. Cells were irradiated with 1,000 J/m² UVB, harvested at the indicated time points, and analyzed by Western blotting. (C) Apigenin inhibits basal COX-2 protein expression as well as UVB-induced COX-2 expression. Immediately after UVB (1,000 J/m²) or sham irradiation, apigenin was added to culture medium to a final concentration of 50 μmol/liter, and cells were harvested at the indicated times. “-” indicates untreated control. (D) UVB-induced PGE₂ synthesis is inhibited by apigenin. 308 cells were treated with UVB, apigenin, or UVB plus apigenin as indicated above, and PGE₂ levels in the culture medium were measured by competitive ELISA.