3 different concentrations for 24 h. Total NADPH content of the cells was measured after 24 h of infection. Data presented here are the mean of 3 independent experiments. PI, primary infection; SI, secondary 14709329 infection; NI: no infection. qRT-PCR. Materials and Methods S1. Acknowledgments We thank Petra Hauck and Alexander Klein for excellent technical assistance and Georg Krohne for electron microscopy and Wilfried Weigel for microarray analysis. Werner Goebel is thanked for critical comments on the manuscript. Harald zur Hausen and the HHV6 foundation is thanked for providing HHV6 virus stocks, HSV-1 was kindly provided by Beate Sodeik,. The Rel/NF-kB transcription factors function in multiple biological processes, including development, immunity, inflammation, and response to cellular stress. NF-kB subunits are often activated in solid or hematological malignancies as the result of rearrangements/mutations in their genes or in genes encoding components of the NF-kB signaling pathway, persistent autocrine or paracrine stimulation through specific cell surface receptors, or viral or cellular oncoprotein activity. NF-kB activation in cancer cells has been shown to activate genes involved in cell survival, proliferation, angiogenesis, invasion, and chemoresistance being therefore an important target for cancer therapy. Recently, an important function for the canonical NF-kB pathway 10336422 in inflammatory cells infiltrating several 
types of solid tumors has been brought to light. NF-kB activation in those cells leads to the production of cytokines, growth factors, and angiogenic factors that promote malignant conversion and progression. The NF-kB proteins are transcriptional regulators that bind cognate DNA elements as homo- or heterodimers. NF-kB activity is controlled by interaction with IkB proteins and only when these are degraded by the proteasome, following serine phosphorylation by IkB kinases and ubiquitination, are NF-kB dimers released. The NF-kB/Rel family comprises five members sharing the conserved Rel homology domain, which is responsible for DNA binding, nuclear localization, dimerization, and IkB binding. In contrast to RelA, RelB, and c-Rel, the p50 and p52 proteins, which derive from proteolytic processing of the p105 and p100 precursor proteins, respectively, lack transactivation domains. The p50 and p52 proteins act thus as transcriptional repressors, except when forming Talampanel heterodimers with other NF-kB members or when interacting with other transcriptional activators, such as the Bcl3 protein. Two main NF-kB activation pathways have been identified. The canonical NF-kB activation pathway, which is triggered by an array of stimuli such as proinflammatory cytokines, antigen receptors, Toll-like receptors, and cellular stress, relies on IKKb /IKKc -dependent IkB phosphorylation and degradation and results in RelA and/or c-Rel activation. Disruption of the canonical pathway in immune cells impairs innate and acquired immune responses in a cell-autonomous or RelB Promotes Leukemogenesis non cell-autonomous manner. The noncanonical NF-kB activation pathway, which can be activated by specific members of the TNF receptor family depends on IKKa and NIK kinase activity but not on IKKb or IKKc. Upon stimulation, IKKa phosphorylates p100 on C-terminal serine residues and induces its ubiquitin-dependent processing to generate p52. When released from p100 sequestration, p52:RelB, p50:RelB, and, as recently shown, p50:RelA dimers shuttle to the
