Epistasis analyses of the effects of RAD1, RAD52, and YKU70 on gamma-ray hypersensitivity. Logarithmic cultures of yeast cells were harvested and resuspended in phosphate-buffered saline, plated onto YEP-dextrose media, and irradiated with the indicated dose of gamma rays. After 3 to 4 days of growth, surviving colonies were counted, and the survival rate was calculated by comparison to the number of colonies from the mock-treated cells. The percentages of survival of RAD⁺ (solid circles), rad1Δ (open diamonds), yku70Δ (solid diamonds), rad52Δ (open squares), rad52Δ yku70Δ (solid triangles), rad1Δ rad52Δ (open circles), rad14Δ rad52Δ yku70Δ (open triangles), and rad1Δ rad52Δ yku70Δ (solid squares) cells are shown. Each experimental point represents the average of three independent experiments.