Photomicrographs of γ-H2AX foci detected in irradiated SF767 cells. Cells were irradiated with 4 Gy, fixed 8 hours later, and then stained with anti-γ-H2AX antibodies. Original magnification × 1,000 (values indicate mean intensity, based on densitometry). (A) γ-H2AX foci in SF767 cells treated with radiation alone. (B) Pretreatment with 5 μ M MP470, before radiation lead to increased γ-H2AX foci. (C) Radiation plus MP470 resulted in a median γ-H2AX foci intensity of 127 compared to 71 for radiation alone p = 0.04.