MG-132 does not decrease DNA-PK activity. PC-3 cells were incubated for 3 hours with MG-132 (50 μM). Cells were washed and incubated at 37°C. At indicated times, cells were lysed and DNA-PK activity was measured by phosphorylation of a human p53 derived oligopeptide in the presence of DNA DSB's. Proteasome inhibition did not cause any significant decrease of DNA-PK activity (n = 2, data expressed as mean ± standard error mean).