IL-1-induced MMP-1 and MMP-13 expression is inhibited in SW-1353 cells preincubated with CDDO for 24 hours. SW-1353 cells were treated for 24 hours with 300 nM CDDO before the addition of 10 ng/ml IL-1β. Alternatively, CDDO was added simultaneously with the cytokine. After a further 18 hours of culture, RNA was harvested, reverse transcribed and subjected to quantitative real-time PCR for MMP-1 (a) and MMP-13 (b). Results were normalized to GAPDH, and are means of culture triplicates. They are expressed as molecules of MMP per molecule of GAPDH. Two-tailed Student's t-tests were performed on the data, and significance is indicated as follows: *P < 0.1; **0.01 <P < 0.05; ***P < 0.01.