To examine CAST activity throughout the development of AD, we probed blots of brain lysates with an antibody against CAST which detects CAST holoprotein at 110 kDa, a number of calpain-cleaved active CAST fragments at 37–75 kDa (which together with CAST holoprotein inhibit calpain) and bands below 37 kDa representing inactive CAST. Here, CAST is linked to Alzheimer disease.