Effect of culture with MDM2 antisense ODN on cell-cycle distribution and apoptosis in RPMI 8226 MM cells. RPMI 8226 MM cells were cultured with MDM2 antisense ODN (A15), media alone, MDM2 sense ODN (S15), or MDM2 scrambled ODN (X15) at concentrations of 1.0 μmol/L for up to 24 hours, without replenishment of ODNs. Cell-cycle distribution (A to D) was defined by PI staining and flow cytometric analysis. The percentage of apoptotic cells (E to H) was determined by acridine orange–ethidium bromide staining.