IL-1-mediated downregulation of PPARγ mRNA expression requires de novo protein synthesis. Chondrocytes were incubated with cycloheximide (10 μg/mL) for 30 minutes prior to stimulation with 100 pg/mL IL-1 for 18 hours. Total RNA was isolated and was reverse-transcribed into cDNA, and PPARγ mRNA was quantified by using real-time polymerase chain reaction. Results are expressed as percentage of control (100 is considered the value of untreated cells) and represent the mean ± standard deviation of four independent experiments. *P < 0.05 compared with cells treated with IL-1 alone. CHX, cycloheximide; IL, interleukin; PPARγ, peroxisome proliferator-activated receptor gamma.