RelA−/−, p50−/− and cRel−/− mice have been described previously (39 (link)). IKKβ+/− mice (40 (link)) were kindly provided by Dr. Zhi-Wei Li (H. Lee Moffitt Cancer Center). E14 wild-type (WT) and RelA−/− fetal liver hematopoietic precursors (CD45.2) were adoptively transferred into lethally irradiated CD45.1 recipient mice as previously described (39 (link)). Recipient mice were typically used after 6–8 weeks. All experiments with mice were carried out in accordance with institutional guidelines. E. coli LPS 0127:B8 (Sigma) was used at 100ng/ml and R837 (imiquimod from Invitrogen) was used at 5μg/ml. The IKKβ inhibitor PS-1145 was used at 10μM and was obtained from Sigma. PS-1145 does not prevent phosphorylation (activation) of IKKβ but inhibits ability to phosphorylate substrates (41 (link)).