The DNA damage response and centrosome surveillance pathway are genetically separable. (A) Immunoblot showing the level of various proteins at 1, 2 or 3 d after addition of DMSO or 3MB-PP1. (B) Fraction of cells with more than five 53BP1 foci at times after addition of DMSO or 3MB-PP1. doxo, doxorubicin; untr, untreated. Data are means ± SEM (n = 3, >50 cells per experiment). (C) Immunoblot showing protein levels in Plk4^AS; Chk2^−/− cells. (D) Representative images of crystal violet–stained colonies. (E) Relative clonogenic survival of 3MB-PP1 or 10 ng/ml doxorubicin–treated Plk4^AS cells. Data are means ± SEM (n = 3). (F) Immunoblot showing protein levels in Plk4^AS; RNF168^−/− cells. (G) Images show the loss of 53BP1 foci formation in doxorubicin-treated Plk4^AS; RNF168^−/− cells. Bar, 5 µm. (H) Graph shows the relative clonogenic survival of Plk4^AS and Plk4^AS; RNF168^−/− cells treated with 3MB-PP1. Data are means ± SEM (n = 3). (I) Graph showing the relative clonogenic survival of 10 ng/ml doxorubicin-treated Plk4^AS cells. Data are means ± SEM (n = 3). ns (nonsignificant), P > 0.05; *, P ≤ 0.05.