Fig. 4.

Deficiency of endogenous C/EBPβ in vivo impairs GH-stimulated c-Fos expression. A, Primary MEF from WT or C/EBPβ deficient (KO) mice were transfected with plasmids for c-Fos-luc, rat GHR, and β-gal; 48 h later, cells were treated with GH for 4 h, and luciferase was measured. Bars represent GH-induced increment in c-Fos promoter activation (mean ± se, n = 3 independent experiments). B, C/EBPβ activates c-Fos promoter in C/EBPβ KO MEF. MEFs from C/EBPβ KO mice were cotransfected with plasmids for c-Fos-luc and the indicated amounts of plasmid for C/EBPβ (μg/well). After 48 h, cells were lysed and luciferase [expressed as relative luciferase units (RLU)] measured. Bars show mean ± se for three independent experiments.