Association of p300 with transcribing SV40 minichromosomes after HDACi treatment. Unfixed SV40 minichromosomes treated with 250 μM NaBu or 120 nM TSA were isolated from cells infected with 776 wild-type virus for 48 hours, immunoprecipitated with RNAPII, and then subjected to an ISFIP/ReChIP analysis with antibody against p300. The samples were amplified by simplex PCR with primer sets to the late region. The position of the amplification product from the wild-type 776 DNA is indicated. Lane 1, ISFIP input fraction; lane 2, ChIP with 7.5 μl of hyperacetylated histone H4 antibody (ISFIP); lane 3, ChIP with 10 μl of p300 antibody (ISFIP); lane 4, ReChIP input fraction; lane 5, ChIP with 7.5 μl of hyperacetylated histone H4 antibody.