(a) Schematic of dual-colored FISH using whole chromosome 11 probe (green) and probe against ATM (red). (b) Representative FISH images of DLD1 cells showing intact chromosome 11’s (Day 0) and broken chromosome 11 fragments containing ATM proximal to the site of breakage at day 1 to 4 post dox induction. (c) Data represent the percentage of spreads with broken chromosome 11 from two independent experiments. 62 mitotic spreads were quantified on Day 0, 53 on Day 1, 48 on Day2, 58 on Day 3, and 61 on Day 4. (d) Representative FISH images showing micronucleation of chromosome 11 fragments with or without ATM foci. (f) Stacked bars represent the percentage of cells with chromosome 11 micronuclei with the indicated number of ATM foci from two independent experiments. 310 cells were quantified on Day 0, 220 cells on Day 1, 190 on Day 2, 214 on Day 3, and 198 on Day 4. (e) Representative FISH images showing ATM foci in primary nuclei. (g) Stacked bars represent the percentage of primary nuclei with the indicated number of ATM foci from two independent experiments. 800 cells were quantified on Day 0, 900 cells on Day 1, 750 on Day 2, 950 on Day 3, and 780 on Day 4.