CENPE and neoplasm: Aneuploidy (that is, the state of having an abnormal number of chromosomes) that results from CENP-E (a kinetochore motor protein) heterozygous knockout appears to inhibit tumorigenesis in p19/ARF−/− mice.24, 25Sgt1 depletion by short interfering RNA (siRNA) in HeLa cells causes delocalization of kinetochore proteins and activation of the weakened spindle checkpoint, which may result in aneuploidy.12, 17, 19 Therefore, we hypothesized that aneuploidy is the mechanism of tumor suppression in Sgt1 heterozygous knockout mice.