Error in Materials and Methods. In the Original Contribution by Fukumoto et al titled "β-Secretase Protein and Activity Are Increased in the Neocortex in Alzheimer Disease," published in the September 2002 issue of the ARCHIVES (2002;59:1381-1389), an error occurred in the "Materials and Methods" section. On page 1382, the homogenization procedure was incorrectly described as being performed at "10 µL/µg (volume per wet weight)," and the BACE ELISA at "0.004 wt/vol." The correct protocol should have read that the tissue was "homogenized in 10 µL/mg volume per wet weight (= 0.1 mg wt/µL vol) of Tris buffer" and that the samples for the BACE ELISA were loaded as "50 µL of 0.001 wt/vol." All dilutions are in the following units: milligrams of wet weight per microliters of buffer volume.