TRAIL and PDBu down-modulate PKCϵ. (A) Detection of endogenous PKCϵ protein in AML cells by Western blot. PKCϵ was revealed by the specific antibody. β-actin was monitored for protein loading. AML cells were treated for 3 days with DMSO (controls), PDBu (20 nM), and TRAIL (25 ng/mL), alone or in combination. PDBu, TRAIL, and, more evidently, their combination, induce a decrease of PKCϵ. A representative experiment is shown. (B) Levels of PKCϵ protein expression in AML cells treated for 3 days with DMSO (controls), PDBu (20 nM), and TRAIL (25 ng/mL), alone or in combination. Densitometric measurements of Western blots from 6 AML samples (means ± SD). *P < .05 versus control; #P < .05 TRAIL plus PDBu versus PDBu alone). (C) Detection of endogenous PKCϵ protein in TF-1, HeL, and K562 cells by Western blot. β-actin was monitored for protein loading. TF-1, HeL, and K562 cells were treated for 3 days with DMSO (controls), PDBu (TF-1, 5 nM; HeL and K562, 20 nM), and TRAIL (25 ng/mL), alone or in combination. Although the different cell lines show different basal levels of PKCϵ expression, PDBu, TRAIL and, more evidently, their combination, invariably induce a decrease of PKCϵ. (D) Levels of PKCϵ proteins expression in TF-1, HeL, and K562 cells treated for 3 days with DMSO (controls), PDBu (TF-1, 5 nM; HeL and K562, 20 nM), and TRAIL (25 ng/mL), alone or in combination. Densitometric measurements of Western blots from 5 independent experiments (means ± SD). *P < .05 versus control; #P < .05 TRAIL plus PDBu versus PDBu alone.