FOXO1 mediates toxicity of SYK inhibitor in tonic BCR signal-dependent DLBCL cells. DHL4, DHL6, Ly1, and Ly7 cells were transduced with pSiren-RetroQ-scrambled-shRNA (Scr shRNA) or pSiren-RetroQ-FOXO1-shRNA (FOXO1 shRNA), and stable transfectants were selected using puromycin. (A) FOXO1, AKT, and SYK protein expression was analyzed by immunoblotting. GAPDH served as a loading control. Densitometric quantification of band intensities is provided in supplemental Table 7. (B) Cells transduced with FOXO1-targeting shRNA vectors were treated with R406 and after 72 hours were analyzed for proliferation using the MTS assay. Please also see supplemental Figure 3 for additional information.