PLK4 is highly expressed in acute myeloid leukemia (AML) patients compared with that in normal human hematopoietic stem cells; levels of PLK4 mRNA and protein are higher in AML cell lines, compared with that in peripheral blood mononuclear cells; PLK4 knockdown induces apoptosis, G2/M arrest and inhibits proliferation and colony formation in AML cells. The gene discussed is PLK4; the disease is acute myeloid leukemia.