Role of MAPK and NF-κB pathways in the IL-1β-induced MMPs, IL-6 expression and PGE2 production in rabbit articular chondrocytes.A-D, Rabbits articular chondrocytes (n=4) were pretreated with PD98059 (30 μM) or BAY11-7082 (10μM) for 2 h followed by IL-1β (10 ng/ml) stimulation for 24 h. Gene expression of MMP-1, MMP-3, MMP-13 and IL-6 was determined by quantitative Real-Time PCR using TaqMan assay. Gene expression of β-actin was used as normalizing control. Each experiment was performed in duplicate. E, Rabbit chondrocytes (n=4) were pretreated with PFE (100 μg/ml) or PD98059 (30 μM) or BAY11-7082 (10μM) for 2 h and then stimulated with IL-1β for 24 h. Changes in PGE2 production were determined using ELISA. Values are shown as Mean ± SE. *P<0.05 **P<0.01