Figure 5

MAPK-mediated signaling in the S1P-induced PGE2 production by HAC. A) Inhibition assays: OA chondrocytes were stimulated in vitro with S1P (10 μM) for 24 h with or without pre-treatment with inhibitor, and levels of PGE₂ in the culture supernatants were subjected to ELISA in triplicate (N = 5). SB: SB203580 (10 μM; p38 MAPK inhibitor), PD: PD98059 (50 μM; ERK1/2 inhibitor), SP: SP600125 (10 μM; JNK inhibitor II), LY: LY294002 (50 μM; PI3K inhibitor). B) Western blot: Chondrocytes (N = 3) were stimulated in vitro with S1P (10 μM) for the indicated time period, and the lysates were analyzed for activations of signaling molecules.