Mitotic kinase activity is higher in AD than in normal brain. Normal and AD extracts were subjected to precipitation with p13suc1-agarose and the precipitates assayed for histone H-1 phosphorylation activity. Representative data from two sets of four normal and four AD cases are shown. Top panels show the histone H1 bands and, with the hippocampus, the position of the GST-p13suc1 fusion product as revealed by Coomassie blue staining. P13suc1-agarose and GST-p13suc1-agarose gave identical results and were used interchangeably. Bottom panels show the corresponding autoradiograms. Phosphorylation of H1 measured by Phosphoimager is higher in AD than in normal brain.