Effects of JUN overexpression on myeloma cell survival. (A) Effects on cell proliferation (left) and cell viability (right) in OCI-My5 (top), OPM2 (middle), and U266 (bottom) cells for JUN overexpression. Total number of cells and cell viability were evaluated daily by trypan blue exclusion. Error bars represent standard error of the mean for 2 independent experiments. (B) JUN overexpression induced apoptosis of OCI-My5, OPM2, and U266 cells as evaluated by flow cytometry performed 72 hours after lentiviral transfection with EV or JUN cDNA. Overexpression of JUN induced a dramatic increase in the percentages of cells with sub–G₀-phase DNA content (indicative of apoptosis). CON indicates control; EV, empty vector; and JUN^H, JUN overexpression.