Fig. 3.

LPS-induced ERK activation is mediated through Toll-like recptor 4 (TLR4). A: MTALs dissected from wild-type and TLR4^−/− mice were incubated in vitro for 15 min at 37°C in the absence (control) and presence of LPS. The tubules were then fixed and stained with p-ERK antibody and analyzed by confocal immunofluorescence as in Fig. 2A. LPS increased ERK phosphorylation in MTALs from wild-type mice but had no effect in MTALs from TLR4^−/− mice. Images are representative of at least six tubules of each type. B: intensity of p-ERK staining was quantified for experiments in A as described in methods and is presented as a percentage of control level measured in the same experiment. *P < 0.05 vs. wild-type control.