TLR4 and colitis: It has been shown that Tpl2 kinase-mediated activation of the Cox-2/PGE2 pathway in intestinal myofibroblasts, which is initiated by macrophage-derived IL-1β as well as TLR4 ligand lipopolysaccharide, is essential for homeostatic responses in the epithelium through promoting epithelial cell proliferation in mice during dextran sodium sulfate-induced colitis [177].