C/EBPβ induces MM cell proliferation and is involved in apoptosis. Proliferation and apoptosis of transfected MM cells with EV, WT-C/EBPβ, or DN-C/EBPβ were analyzed. (A) DNA synthesis was measured by ³H-thymidine incorporation and results are presented as mean of quadruplicates. (B) The graph represents the mean (n = 4) of the percentage of transfected MM cells that have undergone apoptosis measured by annexin V staining. Error bars indicate SD of the mean. (C) Percentage of apoptotic cells of transfected cells was analyzed by annexin V binding/PI staining using flow cytometry. Panel C figure shows a representative experiment of panel B.