(A) OACCs were treated with IL-20 (200 ng/ml) for 8 hours. mRNA was isolated and the transcripts of monocyte chemoattractant protein (MCP)-1, IL-6, MMP-1, and MMP-13 were analyzed using RTQ-PCR with specific primers. The quantification analysis of mRNA was normalized; β-actin was the housekeeping gene. *P < 0.05, **P < 0.01 versus untreated controls. Data are representative of three independent experiments, each done in triplicate. (B) MMP activity in the conditioned media of OACCs treated with IL-20 (200 ng/ml) for 24 and 48 hours. Results are shown as a percentage of the untreated control. **P < 0.01 versus untreated controls. Data are representative of three independent experiments, each done in triplicate. (C) OACCs were treated with IL-20 (200 ng/ml) for 6 hours. mRNA was isolated and the transcripts of TGF-β1, BMP-2, aggrecan, and type 2 collagen (Col 2) were analyzed using RTQ-PCR with specific primers. The quantification analysis of mRNA was normalized; β-actin was the housekeeping gene. **P < 0.01 versus untreated controls. Data are representative of three independent experiments, each done in triplicate.