LPS exposure induces a rapid response in LP cells, followed by secondary epithelial NF-κB activation.  (A–D) Confocal microscopy images of fixed cecae of p65^GFP-FL mice (A–C) or WT mice (D) i.v. injected with (A) PBS or (B–D) LPS and analyzed as indicated. Boxes in overview images indicate insets. Arrowheads indicate p65⁺ nuclei (A–C) or MHCII⁺ cells (D). Arrows indicate p65⁻ nuclei (A–C) or IECs (D). Scale bars: 30 µm (overview images A–C), 20 µm (overview image D), or 10 µm (insets A–C). Representative images of mice from three independent experiments (n = 4–7).