p21 and USP28 are required for the centrosome surveillance pathway. (A and B) Immunoblot showing the levels of p53 or 53BP1 in Plk4^AS; p53^−/− and Plk4^AS; 53BP1^−/− cells. (C and D) Centriole number distribution in interphase Plk4^AS; p53^−/− and Plk4^AS; 53BP1^−/− cells at times after addition of 3MB-PP1. Data are means ± SEM (n = 3, >80 cells per experiment). (E and F) Relative abundance of nuclear p53 in Plk4^AS and Plk4^AS; 53BP1^−/− cells at times after addition of DMSO or 3MB-PP1. Data are means ± SEM (n = 3, >180 cells per experiment). (G) Relative clonogenic survival of 3MB-PP1–treated Plk4^AS cells expressing individual sgRNAs. Data are means ± SEM (n = 2, performed in duplicate). (H) Representative images of crystal violet stained colonies. (I) Immunoblot showing the level of p53 or 53BP1 protein in Plk4^AS; USP28^−/− cells. (J) Relative abundance of nuclear p53 in Plk4^AS; USP28^−/− cells at times after addition of DMSO or 3MB-PP1. Data are means ± SEM (n = 3, >180 cells per experiment). (K) Centriole number distribution in interphase Plk4^AS; USP28^−/− cells at 6 d after addition of 3MB-PP1. Data are means ± SEM (n = 3, >80 cells per experiment). (L) Fold increase in cell number after 3MB-PP1 addition. Data are means ± SEM (n = 2, performed in triplicate). (M) Immunoblot showing the level of p21 or p53 in Plk4^AS; p21^−/− cells. (N) Relative abundance of nuclear p53 in Plk4^AS; p21^−/− cells at times after addition of DMSO or 3MB-PP1. Data are means ± SEM (n = 3, >180 cells per experiment). (O) Centriole number distribution in interphase Plk4^AS; p21^−/− cells at 6 d after addition of 3MB-PP1. Data are means ± SEM (n = 3, >80 cells per experiment). ns (nonsignificant), P > 0.05; *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001.