Figure 1. PLK1 interacts with FOXO1 in vitro and in vivo. (A) 293T cells were transfected with constructs encoding Flag-tagged FOXO1, and co-immunoprecipitation assays were performed. (B) Cell extracts were prepared from HeLa cells and subjected to immunoprecipitation using anti-PLK1 antibodies. (C) Cell extracts were prepared from asynchronous (Asy) or mitotic (M) HeLa cells and subjected to immunoprecipitation using anti-FOXO1 antibodies. (D) In vitro translated FOXO1 was used in a pull-down assay with either GST or GST-PLK1 immobilized on agarose beads. (E) 293T cells were transfected with plasmids encoding Flag-tagged C-terminal truncated FOXO1. Cell lysates were subjected to pull-down assays using beads coated with GST-PLK1. Beads coated with GST alone were used as a negative control. Loading controls are shown on the left (CBB, Coomassie blue staining).