Induction of apoptosis by treatment with FPT-3, FTI-277, or U0126.

NB-4 cells were incubated in the presence or absence of 50 μM FPT3, 50 μM U0126, or 20 μM FTI-277. After 18 hours, cells were harvested and labeling of DNA strand breaks was performed applying the TUNEL method as described in “Materials and methods” (left). M1 indicates no DNA fragmentation; M2, DNA fragmentation. Exposure of phosphatidylserine on the outer leaflet of the plasma membrane was detected using an Annexin V-PE/7AAD double staining method as described in “Materials and methods” (right). Apoptotic exposure of phosphatidylserine is shown in the upper right square. Results are given in percentage of total cell population. (A) Untreated NB-4 cells; (B) solvent-treated (DMSO) NB-4 cells; (C) FPT-3–treated NB-4 cells; (D) FTI-277–treated NB-4 cells; (E) U0126-treated NB-4 cells.