Evidence supporting the role of calpain in the α-processing of amyloid-β precursor protein

► Overexpression of μ-calpain in the cell increased the enzyme activity. ► APP secretion was also increased from this cell. ► Calpain was detected at the cell surface by biotinylation. ► Thus, calpain should be a reasonable candidate for α-secretase. ► Current problems in Alzheimer research are discussed.