NBN foci formation. Double immunostaining of γH2AX (green) and NBN (red) foci in HCC1395 and wildtype cells (MCF10A). Cells were fixed 3 h after irradiation with 1.5 Gy. DNA was counterstained with DAPI. Note the reduced appearance and brightness of yH2AX foci and the absence of NBN foci in the HCC1395 cell line. Scale bar = 5 μm.