IL-1β induces MMP-9 expression via p42/p44 MAPK.

<p>(A) Cells were pretreated with U0126 for 1 h, and then incubated with IL-1β for 12 h. The conditioned media were subjected to determine MMP-9 expression. (B, C) Cells were pretreated with U0126, and then incubated with IL-1β for 4 h (mRNA levels) or 12 h (promoter activity). The mRNA levels and promoter activity of MMP-9 were determined. (D) Cells were transfected with siRNA of scrambled or p42, and then incubated with IL-1β for 12 h. The conditioned media were subjected to determine MMP-9 expression. The protein levels of p42 were determined by Western blotting. (E) Cells were treated with IL-1β for the indicated time intervals or pretreated with U0126, and then treated with IL-1β for 30 min. The phospho-p42/p44 MAPK protein expression was determined by Western blotting. (F, G) Cells were treated with IL-1β for the indicated time intervals. The nuclear fractions were prepared and subjected to Western blotting using an anti-phospho-p42/p44 MAPK antibody. Lamin A was used as a marker protein for nuclear fractions. The translocation of p42/p44 MAPK was observed using a fluorescence microscope. Data are expressed as mean±S.E.M. of three independent experiments. <i>^*P</i><0.05; ^#<i>P</i><0.01, as compared with the cells exposed to IL-1β alone [A, B, C, E (lower panel)] or vehicle alone (E, upper panel).