Figure 1. PP2A activity is inhibited in CML HSCs.
(A) Left: PP2A phosphatase assay (mean ± SD) in CD34+CD38– and CD34+CD38+ cell fractions from NBM and CML donor BM. 32Dcl3 and 32D-BCR-ABL cells were used as controls. Right: SET levels, measured by intracellular flow staining and expressed as MFI (mean ± SD), in CD34+CD38– and CD34+CD38–CD90+ NBM and CML BM cells. (B) Left: Confocal microphotographs showing SET-PP2A association (red signals), as well as quantitative proximity ligation assays (PLA; n = 3), on untreated (UNT) and FTY720-treated (24 hours) CD34+CD38– CML cells. Original magnification, ×630. Right: Western blots showing endogenous SET-PP2Ac association in untreated (lane 1) and FTY720-treated (lane 2) K562 cells. Immunoprecipitation with nonrelated IgG (lane 3) was used as control. *P < 0.05, **P < 0.01, ***P < 0.001.