Figure 5.

Inhibition of PI3K leads to expression of Ikaros and to μHC generation. (A) Immunoblot analysis of FoxO1, Ikaros, and μHC expression in Pten-deficient cells treated with either DMSO or the PI3K inhibitor LY294002. Immunoblotting for actin served as loading control. (B) Flow cytometric analysis of µHC expression in Pten-deficient cells treated with either DMSO or the PI3K inhibitor LY294002. (C) Flow cytometric analysis for µHC and GFP expression of Pten-deficient cells transduced with an EV or an expression vector encoding dominant-negative Ikaros (IK6) and treated with LY294002. (D) Immunoblot analysis for Ikaros expression in SLP-65–deficient pre–B cells treated with DMSO or the PI3K inhibitor LY294002. Immunoblotting for actin served as loading control. (E) Immunoblot analysis for Ikaros expression in SLP-65–deficient pre–B cells transduced with 4-hydroxytamoxifen (4-OHT)–inducible forms of either SLP-65 (ER^T2-SLP65) or FoxO1-A3 (ER^T2-FoxO1-A3). Upon sorting of positively transduced cells, the cells were treated with the solvent ethanol (−) or 4-OHT (+) to activate ER^T2-SLP65 and ER^T2-FoxO1-A3. Immunoblotting for actin served as loading control. (F) Top, FACS plots for κLC expression in SLP-65–deficient pre–B cells transduced with an EV or with an Ikaros expression vector. Cells were cultured in the presence of IL-7. Bottom, dot plots for κLC expression in SLP-65–deficient pre–B cells transduced with an EV or with an expression vector for DN-Ikaros (IK6); both were treated with the PI3K inhibitor LY294002. Numbers in quadrants indicate percentages of cells in the respective region. Data are representative of at least two to three independent experiments.