Effect of TP53 overexpression on MM cell survival. (A) TP53 (in both nuclear and cytosolic extracts) and cleaved PARP (in nuclear extracts) were evaluated by Western blot performed in OCI-MY5 cells after lentiviral infection of TP53 and empty vector (EV) at 4, 8, 12, and 24 hours. Histone H4 and β-tubulin were used as loading controls. (B) TP53 and cleaved PARP were evaluated by Western blot performed in OCI-MY5, JJN3, ARP-1, and Delta 47 cells after lentiviral infection of TP53 and empty vector (EV) at 24 hours. (C) Effect of overexpression of TP53 on cell viability in JJN3, OCI-MY5, ARP-1, and Delta 47 cells. Cell viability was evaluated by trypan blue exclusion every 12 hours after lentiviral infection of TP53 compared with the EV. (D) Overexpression of TP53 induces apoptosis. Cell cycle distribution and apoptosis were evaluated by flow cytometry performed 24 hours after lentiviral infection in JJN3, OCI-MY5, ARP-1, and Delta 47 cells infected with EV or TP53 cDNA. Note that overexpression of TP53 induced a dramatic increase in the percentage of cells with sub-G₀-phase DNA content (indicative of apoptosis).