Inhibition of PP2A by LB100 sensitizes ovarian cancer cells to cisplatin cytotoxicity. A, Structure of LB100, used as the racemate. B, Dose-dependent inhibition of PP2A activity following 2 h LB100 treatment in SKOV-3 cells. B and C, MTT assay after 72 h treatment showing increased cytotoxicity in SKOV-3 cells (C) and OVCAR-8 cells (D) for both IC25 and IC75 doses of cisplatin when cells were pre-treated with LB100 compared to either drug alone. E, Western blots following 48 h treatment shows apoptosis via cleaved PARP and cleaved caspase-3. F, Western blot following 72 h treatment with cisplatin shows that pre-treatment with LB100 enhances apoptosis induced with a sub-lethal dose (IC25) of cisplatin.