C/EBPβ is required for efficient binding of GR, Stat5a, and RXR, but not C/EBPδ, to shared target sites. (A) Lentiviral-mediated knockdown of C/EBPβ expression. 3T3-L1 cells were transduced with lentivirus expressing shRNA targeting LacZ (control) or C/EBPβ, respectively, and cells were induced to differentiate for 4 h. The three different isoforms of C/EBPβ (liver inhibitory protein (LIP), liver activating protein (LAP), and LAP*) are indicated. TFIIB was used as a loading control. C/EBPβ (B), Stat5a (C), GR (D), RXR (E), and C/EBPδ (F) ChIP-PCR for a few selected shared sites 4 h after induction of differentiation of cells expressing shRNA targeting LacZ (control) or C/EBPβ, respectively. Control denotes sites that are occupied by the respective factors but not co-occupied by C/EBPβ. Results are representative of three independent experiments. A full-colour version of this figure is available at The EMBO Journal Online.