FIGURE 3.

Aβ induces rapid activation of caspase 3/7 and calpain proteases. A and B, direct activity measurements were performed as described under “Experimental Procedures” as a function of time exposed to Aβ without (−) or with (+) the respective protease inhibitor pretreatment. Data were normalized to 1 for mock-treated controls (Un). Error bars represent the S.E. of three independent experiments. *, p < 0.01 compared with controls. C and D, an immunoblot analysis verifies protease activity with substrate cleavage. Calpain substrate spectrin and caspase substrate vimentin demonstrate cleavage into smaller molecular weight fragments upon Aβ treatment, both of which are protected by the respective inhibitors.