FIGURE 3.
DLs rapidly activate MAPK p38 and its target gene HSP-27, which is blocked by the caspase inhibitor or cFLIP isoforms/mutants. A, control infected keratinocytes and keratinocytes expressing cFLIPL or cFLIPS were stimulated with TRAIL (0.5 μg/ml) for the indicated time points. Cellular lysates were subsequently analyzed for the phosphorylation of MAPK p38 using phospho-specific antibodies. Membranes were stripped and total levels of p38 were determined to confirm even loading of proteins. B, control cells or cells expressing the different cFLIP isoforms or mutants, respectively, were preincubated for 1 h in the presence or absence of Z-VAD-fmk (20 μm), and subsequently stimulated for 15 and 30 min (B) or 2 h (C), respectively, with TRAIL (0.5 μg/ml). Total cellular lysates were characterized for p38 phosphorylation and HSP-27 phosphorylation. One of three independent experiments is shown.