Proteolytic processing of overexpressed ephrin-B1 derivatives. A) Proteasome and γ-secretase inhibitor ("epo" and "DAPT", respectively) treatments on cells expressing eB1ΔE (black arrowhead). Proteolytically-generated ICD was shown by asterisk. DAPT inhibited the processing of eB1ΔE as well as endogenous APP (accumulation of C-terminal stub, white arrowhead in lower panel). B) Cell-free assay using COS membrane expressing eB1ΔE. de novo generated ICDs from eB1ΔE (black arrowhead) and APP C-terminal stub (white arrowhead) were indicated by asterisk and double asterisks, respectively. C) Inhibitor treatments (same as A) on cells expressing eB1ICD (asterisk). Accumulation of C-terminal stub (white arrowhead) by DAPT was shown at lower panel.