FIG. 1.

Proteasome inhibitor MG115 sensitizes primary keratinocytes to TRAIL-induced apoptosis. (A) Primary keratinocytes were treated with 50 ng of TRAIL per ml for 16 h. Caspase-dependent cytotoxicity of TRAIL (sub-G₀ DNA analysis) is only detectable in the presence of the proteasome inhibitor MG115 (10 μM). zVAD-FMK (40 μM) completely abolishes TRAIL-induced apoptosis. (B) Dose-dependent effect of MG115 on TRAIL-induced cell death in primary keratinocytes was determined by crystal violet staining 16 h after addition of the indicated concentrations of TRAIL.