Effect of culture with MDM2 antisense ODN on expression of MDM2, phosphorylation of pRB, and pRB–E2F-1 binding in RPMI 8226 MM cells. RPMI 8226 MM cells were cultured with 1.0 μmol/L MDM2 antisense ODN (A15) for up to 24 hours. Cell lysates prepared before and at 0.5, 1, 2, 4, 6, 8, 16, and 24 hours were immunoprecipitated with SMP-14 anti-MDM2 MoAb and blotted with the same Ab (A). Cell lysates were immunoprecipitated with Ab-1 C36 anti-pRB MoAb, followed by immunoblotting with Ab-6 AF11 anti-pRB MoAb (B) or C-20 anti–E2F-1 MoAb (C).