PTPA and acute myeloid leukemia: We also observed that penfluridol exhibited more-potent cytotoxicity against FLT3-ITD AML cells (MV4–11) than FLT3-WT AML cells (HL-60 and U937), which might have been due to FLT3-ITD cells displaying lower PP2A activity than FLT3-WT cells [11].