MG-132 sensitizes human cancer cell lines to ionizing radiation. PC-3 prostate cancer cells were incubated with MG-132 (50 μM) for 3 hours, washed twice, irradiated and plated into culture dishes. After 14 days the colonies were fixed with ethanol, stained with crystal violet, and counted. MG-132 treatment sensitized PC-3 cells to ionizing radiation. Radiobiological parameters obtained from a linear-quadratic fit (LQ-fit): PC-3 control α = 0.3, β = 0.043, α/β = 7.6; PC-3 MG-132 α = 0.3, β = 0.07, α/β = 4.3. Data shows means (± standard deviation) from 3 experiments (each plated in triplicates).