Addition of APP-TM peptides to HEK293 cells affects APP processing and leads to an increase in γ-secretase substrates. HEK293 cells were incubated overnight with APP-TM peptides. The cells extracts were separated by SDS-PAGE and probed by western blotting with an APP C-terminal antibody (Sigma). See Blue plus-2 (Invitrogen) molecular weight markers were used. Total protein concentration was the same in each lane. There is a noticeable increase in the amount of γ-secretase substrates (α- and β-stubs) relative to untreated cells.