Nutlin-3 induces p21 in pseudo-G1 cells when combined with MK-0457. (A) OCI-AML-3 cells were treated for 24 hours with 2.5 μM Nutlin-3 and 10 nM MK-0457, either as individual agents or in combination. p21 expression levels and DNA content were measured by flow cytometry. Open histograms show staining with isotype controls. Data were gated on the FL2-area versus FL2-width cytogram to exclude doublets. Results are representative of 3 independent experiments. (B) After 48 hours of treatment, aberrant p21 expression was observed in cells with 8N as well as 4N DNA content. (C) Parental HCT116 cells (p21+/+) or p21-deficient HCT116 cells (p21−/−) were treated for 48 hours with 10 nM MK-0457 and 10 μM Nutlin-3, either as individual agents or in combination. Nutlin-3 caused G1-phase cell- cycle arrest and inhibited MK-0457-induced endoreduplication more prominently in p21+/+ cells than p21−/− cells. Results are representative of 3 independent experiments.
