Figure 2.

PD98059 inhibited the UVB-induced ERK1/2 activation. PECs were seeded at equal density and cultured until 95% confluence was established. Cells were serum starved overnight then either irradiated with 20 mJ/cm² UVB (A and G) or mock irradiated (B), and immediately treated with the ERK inhibitor PD98059 (25 μmol/L final) (C, D, and H). Total cell lysates were prepared at the indicated times ranging from 5 minutes to 7 hours. Western blot analysis was performed (A–D, G, and H) with phospho (P)-specific P-p44/p42 (A–C) and phospho-specific P-p38 (G and H) antibodies or antibodies directed against total (T)-p44/p42 (ERK) (D). Equal protein loading was confirmed by staining the SDS-PAGE gels with Coomassie Blue. The Western blot results were further semiquantified and comparisons made between UVB-irradiated and mock-irradiated PECs (E) and UVB-exposed and PD98059-treated PECs (F) with respect to phospho-ERK (pERK) expression. These results are representative of three different cell lines analyzed.