(A-D) OASFs were treated with IL-20 (200 ng/ml) for 4 and 8 hours. mRNA was isolated and the transcripts of tumor necrosis factor (TNF)-α, IL-1β, matrix metalloproteinase (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. (E) MMP activity in the conditioned media of OASFs treated with IL-20 (200 ng/ml) for 24 and 48 hours. Results are shown as a percentage of the untreated control. *P < 0.05, **P < 0.01 versus untreated controls. Data are representative of three independent experiments, each done in triplicate. (F) OASFs were incubated with IL-20 (200 ng/ml) for the indicated time periods. Total cell lysates were analyzed using Western blotting with specific antibodies against phosphor-ERK-1/2, JNK, and β-actin. Data are representative of three independent experiments.