Extended Data Fig. 10: ARP2/3 inactivation confers sensitivity to DSBs induced in S-phase as well as replication-stress-inducing agents.

a, Control CB33 lymphocytes or lymphocytes bearing a V75M mutation in the WAS gene were treated with CPT for 0, 12, or 24 h. Per cent viability following CPT treatment was assessed by measuring the fraction of annexin V- and PI-negative cells by flow cytometry. b, Summary of CB33 or WAS V75M lymphocyte survival following CPT treatment. P calculated by two-way ANOVA with multiple comparisons; data shown as mean and s.d.; n = 3 independent experiments. c, Clonogenic U2OS cell survival after 12 h of CPT treatment in the presence of DMSO or increasing concentrations of CK-666. Triplicate experiments; data shown as mean and s.d.; n = 2 independent experiments. d, Clonogenic U2OS cell survival after 12 h of aphidicolin treatment in the presence of DMSO or increasing concentrations of CK-666. Triplicate experiments; data shown as mean and s.d.; n = 2 independent experiments. e, Clonogenic U2OS cell survival after olaparib treatment in the presence of DMSO or increasing concentrations of CK-666 for 14 days. Triplicate experiments; data shown as mean and s.e.m.; n = 2 independent experiments. f, DNA damage induces DSBs, which are repaired preferentially by NHEJ in mammalian cells (blue). In S/G2, DSBs may be repaired by HDR (red). All DSBs recruit WASP, but ARP2/3-dependent actin polymerization occurs only at HDR breaks, which become more mobile. Actin polymerization in the vicinity of DSBs generates forces that result in DSB clustering, optimal DNA end resection, formation of RAD51 foci, and HDR.