Fig. 3.

Effects of various reagents on Con A cap formation and membrane-bound PKC activity in normal cell lines. (a) After the cells (1×10⁶/ml) were cultured overnight with or without E-64-d (1 μg/ml), the cells were treated with chelerythrin (1 μm;) or C2-ceramide (3 μg/ml) for 2 h. FITC-Con A (20 μg/ml) was then added and incubated for 30 min at 37°C. Con A cap formation was determined as described in Patients and methods. The column represents the mean ± s.e. of at least four experiments. E, E-64-d; Ch, chelerythrin; Cer, C₂-ceramide. *P < 0.01 compared with medium alone. (b) After the cells (1×10⁶/ml) were treated with chelerythrin (1 μm) or C2-ceramide (3 μg/ml) for 2 h, Con A (20 μg/ml) was added and incubated for 20 min. In some experiments, cells were preincubated overnight with E-64-d (1 μg/ml) before treatment with chelerythrin or C₂-ceramide. PKC activity was assayed in the membrane fractions as described in Patients and methods. The data are means (pmol/min/10⁷ cells) of at least three experiments. The s.e. of each column was less than 10%. E, E-64-d; Ch, chelerythrin; Cer, C₂-ceramide.