Loss of KIF18A function does not alter chromosome copy number. (A) Image of an hTERT-RPE1 cell with chromosomes 9 (red) and 22 (green) labeled by FISH. (B) Plot of the percentage of cells aneuploid for the indicated chromosomes following treatment with control siRNA, KIF18A siRNA, or MAD2 siRNA. n = 1,500 cells for each condition from three independent experiments; *, P < 0.05 based on χ² analyses. The effect of MAD2 KD on chromosomes 2, 3, 7, or 9 was not determined. (C) Image of Geimsa stained metaphase spread of an early passage (p0) MEF. (D) Quantification of metaphase chromosome numbers from WT and Kif18a^gcd2/gcd2, early passage (p0), pair-matched MEFs (top); hTERT-RPE1 cells treated with control or KIF18A siRNAs (middle); and control and KIF18A KO RPE1 cells (bottom). Indicated P values were calculated by χ² analyses. Data were collected from three independent experiments for Kif18a^gcd2/gcd2 MEFs and siRNA-treated cells. Data were collected from two independent experiments for KIF18A KO hTERT-RPE1 cells.