HHV-8 acute infection induces IKK and NF-κB activities in HUVECs. HUVEC monolayers were mock infected (control) or infected with HHV-8 or treated with TPA (20 ng/mL). At different times after infection, whole-cell extracts were prepared and analyzed for NF-κB activation by EMSA (A) or for IKK activity and recovery by kinase assay (KA) and immunoblotting (IB), respectively (B). Sections of fluorograms from native gels are shown (right panels). Position of NF-κB-DNA (NF-κB) and nonspecific protein-DNA (ns) complexes are indicated. The levels of NF-κB and IKK activity in HHV-8–infected cells were quantified by MDP analysis and expressed as fold induction of the levels detected in uninfected control cells (left panels). Results of a representative experiment of 3 with similar results are shown. (C) HUVEC monolayers were mock infected (C), infected with HHV-8 (HHV-8), or treated with 20 ng/mL TPA. At 4 hours after infection whole-cell extracts were subjected to competition EMSA by using the oligonucleotide containing the consensus NF-κB element as a probe in the absence (−) or the presence (25X) of 25-fold excess unlabeled consensus oligonucleotide.