FIGURE 7.

Block to RNA polymerase II recruitment to Fra-1 during differentiation. C2C12 cells were rendered quiescent (left panel) by culturing in 0.1% FBS for 3 days or differentiated (right panel) by culturing in 2% horse serum for 6 days. Subsequently, the cells were restimulated for 8 h in the presence of 20% FBS. ChIP analysis was performed with antibody to Pol II or IgG as control. Sequences spanning the E boxes in intron 1 of Fra-1 (Fra-1 int1), the transcriptional start site of Fra-1 (Fra-1 TSS), ∼3 kb downstream of the Fra-1 intronic E boxes (Fra-1 3 kb), and the MCK enhancer (MCK) were analyzed by PCR. One-tenth of the lysates used for ChIP were also subjected to PCR (input, In). The results are representative of at least two independent experiments.