Chromatin Immunoprecipitation (ChIP) assays were performed as described [104] . Briefly, cells were cross-linked with 1% formaldehyde and sonicated nuclear extracts were mock-immunoprecipitated or immunoprecipitated with anti-tetraacetylated histone H4 (Upstate). Recovered DNA aliquots from these samples and from input extracts were amplified with real-time PCR using the LightCycler II system (Roche) and Quantitect SYBR Green PCR Kit (Qiagen). Enrichments at specific chromatin loci are shown as the amount of immunoprecipitated DNA in the percent of total input chromatin. The following primers were used: IL -6  promoter: TGG GGA TGT CTG TAG CTC ATT and CAT  AGC GGT TTC TGG AAT TGA, TNF promoter: GGG CAG  CCC CAG AGG GAA TGA ACT C and TAT GGC AGA GGC  TCC GTG GAA AAC TCA CT, Topoisomerase 3b promoter: AGT CCG AGA ACA GCC TGG GT and AGT TGT GCT GCC CAC AGA GG, l5 promoter: TCC CCA TTG CCA GAT AGA GAC ACA and TGG GCC CAA CAG ATT AAC ACA GAG.