KIF18A depletion led to a widening of the metaphase plate and oscillatory chromosome movements as well as high levels of chromosome missegregation in tetraploid, but not diploid, normal and cancer cells (Quinton et al., 2021), suggesting that high KIF18A levels might be required to temper microtubule dynamics in WGD+ cells. The gene discussed is KIF18A; the disease is cancer.