['The study aimed to analyze the impact of the proteasome inhibitors MG132 (N-carbobenzyoxyl-L-leucyl-L-leucyl-L-leucinal), lactacystin and celastrol on manganese superoxide dismutase (MnSOD), catalase and glutathione-S-transferase-π (GST-π), and on the heat shock protein 70 (Hsp70) in human peripheral blood mononuclear cells (PBMC), exposed to ionizing radiation.', 'Changes in protein levels were analyzed by Western blot. Cellular viability, proteasome activity, level of oxidative stress and apoptosis were determined by standard colorimetric and fluorescence assays.', 'MG132 and lactacystin induced an increase in the intracellular levels of Hsp70. MnSOD was up-regulated by MG132 and celastrol, and GST-π was up-regulated by MG132 and lactacystin. Notably, the proteasome inhibitors significantly modified the protein levels in the irradiated cells and dramatically reduced the intracellular pool of oxidative species. The combined effect of radiation and proteasome inhibition was a dose-dependent up-regulation of the antioxidant enzymes and Hsp70.'] Does proteasome inhibition protect human peripheral blood mononuclear cells from radiation-induced oxidative stress?