FIG. 7.
Gfi-1B is required for imatinib-induced apoptosis in K562 cells. K562 cells were transfected with Gfi-1B siRNA or control siRNA. After 24 h, cells were treated with or without 1 μM imatinib for an additional 48 h. (A) Western blot analysis with anti-Gfi-1B, anti-Bcl-xL, or β-tubulin antibody (Ab; left panel) and semiquantitative RT-PCR assay using primers specific for Gfi-1B, Bcl-xL, and the GAPDH gene (right panel). −, absent; +, present. (B) The effect of Gfi-1B siRNA transfection on the imatinib-induced up-regulation of Gfi-1B (left panel) and down-regulation of Bcl-xL (right panel) was evaluated by densitometric determination of the protein expression levels, which were normalized by the β-tubulin level in the corresponding sample. Values are the averages of results from three independent experiments. The error bars represent standard deviations. (C) Cells were also harvested and analyzed by annexin V-FITC staining. Values are the averages of three independent determinations. The error bars represent standard deviations. *, P < 0.05.