Regulation of gene expression by c-Rel. (a) p35, p40, and p19 expression in APCs. DC-enriched APCs from normal and c-Rel–deficient C57BL/6 mice were cultured with or without (–) LPS for 5 hours as described in Figure 5 legend. Total RNA was extracted, and gene expression was determined by RT-PCR as described in Methods. (b) T-bet expression in T cells. CD4+ T cells were isolated and treated as described in Figure 9, and their nuclear extracts were prepared 48 hours after the second stimulation. T-bet expression was determined by Western blot as described in Methods.