Fig. 6. Proteasome inhibition increases the amount of TACE substrates at the surface of TACE-inhibited cells. Native cells and ECV-304 cells stably expressing TNF- were treated with Ro 32-7315 (5 µM) 15 minutes before the addition of vehicle alone (Cont), MG-262 (600 nM) or PMA (20 nM) as indicated. Four hours later, cell surface expression of ectopic TNF- (black bars) and endogenous TNFR1 on native ECV-304 cells (white bars) were measured by flow cytometry. Experiments were performed in duplicate and repeated three times. Significance of difference between treated and control cells: **, P<0.001.