Figure 3.
Bi-phasic effects on ERK phosphorylation in response to BrdU photolysis. (A) U87 cells were treated with BrdU, Hoechst dye and increasing doses of UV-A [0 J/m2 (lanes 1 and 9); 15 J/m2 (lanes 2 and 10); 50 J/m2 (lanes 3 and 11); 150 J/m2 (lanes 4 and 12); 500 J/m2 (lanes 5 and 13); 1,500 J/m2 (lanes 6 and 14); 3,000 J/m2 (lanes 7 and 15) and 6,000 J/m2 (lanes 8 and 16)]. Cells were collected at 3 and 6 h and analyzed by western blotting. ERK and β-actin denote equal loading. (B) Time course response of ERK phosphorylation. U87 cells were labeled with BrdU, treated with Hoechst dye and irradiated with UV-A at 150 J/m2 (+) or not (−). Cells were collected at 1, 3 and 6 h after UV-A treatment for western blotting and quantification by densitometric analysis. (C) UV-A dose response. U87 cells were labeled with BrdU, treated with Hoechst dye and irradiated with UV-A at 15, 50, 150, 500 and 1,500 J/m2 or left untreated (0). Cells were collected after 3 h for western blot analyses and subsequent densitometric determination. Data points, ERK phosphorylation levels. Error bars, SEM; n = 3. Fold (x) denotes changes in p-ERK levels compared to control (no UV-A) normalized to total ERK protein levels. *p < 0.05.