Figure 4.

BRC4 overexpression in cells inhibits ionizing radiation (IR)-induced RAD51 foci formation, whereas BRC5 does not. (a) Doxycycline-induced, myc-BRC4- or -BRC5-expressing cells were treated with IR (5 Gy) and fixed 4 h later for immunostaining with anti-RAD51 and anti-myc antibodies. Cells containing more than 15 foci were counted as positive for RAD51 foci formation. The mean±s.e.m. from three independent experiments is shown. The number of cells examined in each sample was ⩾100. (b) Representative micrographs showing RAD51 foci formation in BRC-repeat-expressing cells. DNA in blue, RAD51 in green and myc in red are shown. Scale bar is 5 μm.