Fig. 7. APP shedding assay. HEK293 cells were transfected with SEAP-APP, ß-gal and empty vector (Topo) or with a plasmid encoding wild-type BACE, a catalytically inactive BACE mutant (BACE D93/289A), non-phosphorylated BACE mutant (BACE S498A), pseudophosphorylated BACE mutant (BACE S498D) or BACE dileucine mutant (LL 499/500 AA). The alkaline phosphatase activity in the conditioned medium is shown, normalized to ß-gal activity, with the means and SD after both transfection and measurement were carried out in triplicate, representing two independent assays. **, P<0.001 (ANOVA, Fisher's PLSD post hoc test).