FIG. 6.

Kinetics of caspase activation and cleavage in Stx1-treated THP-1 cells. (A) Cells were incubated with or without Stx1 (400 ng/ml) for 0 to 24 h. Caspase-3, -8, and -9 activities were then assayed as described in Materials and Methods. Control cells have not been treated with Stx1. Data shown are means ± standard errors of the means from three independent experiments (B) After Stx1 stimulation for 0, 2, 4, 6, and 8 h, cell lysates were subjected to SDS-PAGE and caspase-3, -8, and -9 cleavage was detected by immunoblotting with antibodies directed against the caspases. Data are representative of three independent experiments.