Micronuclei in KIF18A-deficient cells successfully recruit the noncore nuclear envelope component lamin B. (A) Representative images of fixed, micronucleated RPE1 cells labeled with DAPI (DNA, blue), ACA (centromeres, green), and lamin B (red). (B) Plot displaying lamin B fluorescence in micronuclear envelopes. Data are from three independent experiments. n = 27 (RPE1 + nocodazole washout), n = 28 (KIF18A KO). *, P < 0.001. Data points indicate individual micronuclei. (C) Plot displaying the ratio of lamin B fluorescence in the micronuclear envelope to lamin B recruited to the primary nuclear (PN) envelope of the same cell. Data are from three independent experiments. n = 10 (RPE1 + nocodazole washout), n = 14 (KIF18A KO). *, P < 0.0001. Data points indicate individual micronucleated cells. (D) Plot displaying the ratios of lamin B in the micronucleated envelope to lamin B in the PN envelope, parsed by continuous, incomplete, or absent lamin A/C recruitment, as assessed by costaining with lamin A/C antibody. n = 24 (RPE1 + nocodazole washout), n = 52 (KIF18A KO). *, P < 0.01. Data are from three independent experiments. Data points indicate individual micronucleated cells. (E) Representative images of thymic lymphoma tumor sections stained with Hoechst (DNA, blue) and lamin B (nuclear envelope, red); micronuclei indicated by yellow arrowheads. (F) Plot showing percentage of micronuclei in thymic lymphoma tissues that lacked lamin B. n = 3 biological replicates per genotype (also see Table S9). Data points indicate individual biological replicates. Indicated P values for numerical data were obtained using unpaired Student’s t test for comparisons between two conditions or a one-way ANOVA with Tukey’s post hoc test for comparisons among more than two conditions. Noc., nocodazole.