Inhibition of Aurora kinase activity induces endoreduplication in AML cells. (A) AML cells were treated for the indicated time with 10 nM MK-0457 or 2.5 μM Nutlin-3. MK-0457 induced time-dependent endoreduplication of the cells irrespective of the p53 status. Nutlin-3 caused G₁-phase cell-cycle arrest only in wild-type p53 OCI-AML-3 and MOLM-13 cells. Results are representative of 3 independent experiments. (B) Expression of phosphorylated histone H3 in AML cells after 24 hours of treatment with 10 nM MK-0457. MK-0457 abrogated histone H3 phosphorylation on Ser¹⁰ . Results are representative of 3 independent experiments.