IL-1β promotes GA cell migration and invasion by activating p38. A: Western blots confirmed that p-p38 could be induced by 30 min stimulation with IL-1β in AGS and MKN-45 cell lines; the activation of p38 by IL-1β was inhibited by p38 inhibitor SB202190. B: Transfection of p38 siRNA knocked down p38 expression in both the two GA cell lines. C-F: Treatment of GA cells with IL-1β increased cell migration and invasion in vitro; these effects were inhibited by p38 siRNA or the p38 pathway inhibitor SB202190. **P < 0.05 vs. scramble siRNA (Control siRNA)-transfected cells stimulated with IL-1β; △△P < 0.05 vs. untransfected cells (wild type cells) stimulated with IL-1β. Bars indicate the mean ± SD number of cells per field of view (× 400 magnification) in the migration and invasion assays. G: Representative light microscope images of AGS and MKN-45 cell migration and invasion in the Transwell assays.