RBP-J inhibits TNF-induced c-Fos expression and function. (A) Immunoblot analysis of c-Fos and c-Jun in nuclear and cytoplasmic fractions of Rbpj^+/+ and Rbpj^ΔM/ΔM BMMs obtained at the indicated time points after stimulation with TNF. TBP and p38 were measured as loading controls for nuclear and cytoplasmic fractions, respectively. (B) ChIP analysis of c-Fos occupancy at Nfatc1 promoter in Rbpj^+/+ and Rbpj^ΔM/ΔM BMMs treated without or with TNF for 40 h. **, P < 0.01. (C) Immunoblot analysis of c-Fos in Rbpj^+/+ and Rbpj^ΔM/ΔM BMMs transfected with Fos-specific short interfering RNAs (Fos) or nontargeting control siRNAs (Control), and treated with TNF for 16 h. (D and E) Osteoclastogenesis assays of Rbpj^+/+ and Rbpj^ΔM/ΔM BMMs transfected with siRNA targeting Fos mRNA or nontargeting control siRNAs (Control) in the presence of TNF. TRAP staining is shown in D and quantitated in E. Bar, 50 µm. **, P < 0.01. Data are representative of at least three independent experiments (A–E).