Inefficient DISC formation in SW948-TR cells. A: Membrane expression of the TRAIL receptors DR4 and DR5 in SW948 and SW948-TR cells as determined by flow cytometry. Values are expressed as the mean fluorescence intensity (MFI) and are mean ± SE of at least three independent experiments. B: Analysis of the TRAIL-DISC in SW948 and SW948-TR. Cells were incubated for 30 min with Flag-tagged TRAIL and the assembled DISCs were immunoprecipitated and analyzed by Western blotting using antibodies to DR4, DR5, FADD, caspase 8 and c-FLIP. T = total cell lysates; C = control of immunoprecipitation, IP = immunoprecipitation (After a longer exposure DR5 bands were also detectable in the total cell lysates (T)). C: Western blot analysis comparing caspase 8 levels in SW948 and SW948-TR cells. One of at least three independent experiments is shown.