Figure 6.

Effect of mitogen-activated protein kinase, nuclear factor-kappa-B, and Notch inhibitors on interleukin-1-beta (IL-1β)-induced upregulation of lipocalin-type prostaglandin D synthase (L-PGDS) expression. Osteoarthritis chondrocytes were pretreated with SB203580 (1 μM), SP600125 (10 μM), PD98059 (10 μM), or SN-50 (1 μM) for 30 minutes (a) or with increasing concentrations (1, 5, and 10 mM) of DAPT for 48 hours (b) prior to stimulation with IL-1β (100 pg/mL). After 48 hours, cell lysates were prepared and analyzed for L-PGDS and β-actin protein expression by Western blotting. Representative Western blots are shown in the upper panels. In the lower panels, the bands were scanned, and the L-PGDS band intensity values were normalized to the corresponding β-actin band intensity value. Data are expressed as fold induction, considering 1 as the value of unstimulated cells, and represent the mean ± standard error of the mean of four independent experiments. *P < 0.05 compared with cells treated with IL-1β alone. DAPT, N-[N-(3,5-diflurophenylacetate)-L-alanyl]-(S)-phenylglycine t-butyl ester.