Figure 4. TNF- stimulates the IL-6 gene promoter via p38 MAPK, NFB, and C/EBPß. (Panel A) MG-63 cells were transiently transfected with respective plasmid (phIL-6 wild-type [phIL-6WT] or 5'-deletion constructs [phIL-6A and phIL-6B]), serum-starved for 24 hrs, and then stimulated with TNF- (10 ng/mL) for 24 hrs. p38 MAPK inhibition was achieved by pre-incubation with SB203580HCl (10 µM) for 1 hr immediately prior to TNF- stimulation (10 ng/mL). Luciferase activity within cell lysates was measured and corrected for transfection efficiency. *Statistically significant difference from TNF--stimulated cultures (p < 0.05). Bars represent mean ± standard deviation (n = 3), relative to control (unstimulated cultures). (Panel B) TNF- modulates NFB- and C/EBPß-sensitive promoters via p38MAPK. Cells were transiently transfected with respective plasmid (or vector only), serum-starved for 24 hrs, and then stimulated with TNF- (10 ng/mL) for 24 hrs. p38 MAPK inhibition was achieved by pre-incubation with SB203580HCl (10 µM) for 1 hr immediately prior to TNF- stimulation. Luciferase activity within cell lysates was measured and corrected for transfection efficiency. *Statistically significant difference from control (unstimulated) cultures (p < 0.05). Bars represent mean ± standard deviation (n = 4).