E4bp4−/− mice after delirium induction showed increases in total phosphorylated proteins of ERK1/2 and p65 (an NF‐κB subunit and a downstream target of ERK1/2) in the hippocampus (Figure7A,B), and an elevation in nuclear phosphorylated ERK1/2 and p65 (Figure 7C). Here, MAPK3 is linked to delirium.