Involvement of p38 MAP kinase. A) Human astrocytes were pretreated for 1 h with the p38 MAPK inhibitor SB203580 or MEK1/2 inhibitor U0126 (3, 10, 30 μM) prior to IL-1β (10 ng/ml) exposure for 72 h. Culture supernatants were collected to measure NO levels by Griess reagent. Data presented are mean ± SE of triplicates of 2-3 separate experiments using astrocyte cultures from different brain tissue specimens. **p < 0.01 vs. untreated control (C); ††p < 0.01 vs. IL-1β alone. B) After replacing culture media with DMEM without serum, human astrocytes were treated with hemin (20 μM) for 24 h prior to IL-1β (10 ng/ml) exposure for 30 min. Cell lysates were electrophorezed, transblotted to nitrocellulose membrane and probed for p38 or p44/42 MAPK or β-actin (as internal control). Data presented are representative of 3 separate experiments using different brain tissue specimens.