Expression of MDM2 protein in MM-derived cell lines. PCL patients cells, Saos-2 osteosarcoma cells, and normal BM MNCs. Total cell lysates of MM cell lines (ARH-77, RPMI 8226, and OCI-My5), cells from PCL patients (PCL1 and PCL2), Saos-2 p53-deficient osteosarcoma cells, and normal BM MNCs (without and 1 and 4 hours post-XRT) were immunoprecipitated with SMP14 anti-MDM2 MoAb followed by immunoblotting with the same Ab. Immunoprecipitation and immunoblotting with AB-1 anti-actin MoAb confirmed equal protein loading.