Tyrosine kinase and PI3K's involvement in LTA-mediated p38 MAPK activation in RAW 264.7 macrophages. In (a) and (b), cells were incubated with LTA (10 µg/ml) for various time intervals (a) or various concentrations of LTA for 30 min (b). Whole-cell lysates were prepared and subjected to Western blot analysis using antibodies specific for phosphorylated p38 MAPK (p-p38) or p38 MAPK (p38) as described in ‘Materials and methods’. In (c), cells were pretreated with 100 nm wortmannin, 30 µm LY 294002, 20 µm tyrphostin AG126, 30 µm genistein, or 10 µm SB 203580 for 30 min before incubation with LTA (10 µg/ml) for 30 min. Whole-cell lysates were prepared and subjected to Western blot analysis using antibodies specific for phosphorylated p38 MAPK (p-p38) or p38 MAPK (p38) as described in ‘Materials and methods’. Typical traces represents three experiments with similar results. Wort, wortmannin; LY, LY 294002; Tyrp, tyrphostin AG126; Geni, genistein; SB, SB 203580.