MDM4 expression levels were elevated in CK-AML patients relative to NK-AML patients, MDM4-overexpressing HepG2 cell lines had a reduced mitotic index, reduced p21, BubR1 or Securin expression levels following Nocodazole treatment, and MDM4-overexpressing cells were aneuploidy or polyploidy. The gene discussed is MDM4; the disease is acute myeloid leukemia.