ETAA1 suppresses mitotic chromosome abnormalities associated with incompletely replicated DNA. (A) Workflow for analysis of mitotic chromosome abnormalities. (B) Quantification of DAPI-positive chromatin bridges (example shown in inset) in anaphase HCT116 cells treated as in A (mean ± SEM; n = 3 independent experiments; 100 anaphases/condition; unpaired t test). (C) As in B, except that the proportion of cells with lagging chromatin (inset) was quantified (mean ± SEM; n = 3 independent experiments; 100 anaphases/condition; unpaired t test). (D) Representative images of PICH-coated UFBs in anaphase HCT116 cells treated as in A and coimmunostained with PICH and FANCD2 antibodies. FANCD2 foci at UFB termini demarcating CFSs can be seen. (E and F) Quantification of data in D (mean ± SEM; n = 3 independent experiments; 120 anaphases/condition; unpaired t test). (G) Representative images showing breaks (indicated by arrows) on metaphase chromosomes from APH-exposed HCT116 cells treated as in A. (H) Quantification of data in G. Box plot shows the median, upper and lower quartiles (boxes), and 10th and 90th percentiles (whiskers; 25–35 metaphases/condition; Kruskal–Wallis test). (I) Representative images of EdU incorporation in prometaphase nuclei demarcating MiDAS in HCT116 cells treated as in A. (J) Quantification of data in I (red bars, median; n = 3 independent experiments; 120–130 prometaphases/per condition; Kruskal–Wallis test). ****, P < 0.0001; ***, P < 0.0005; **, P < 0.005; *, P < 0.05; ns, not significant. Scale bars, 2 µm.