MAPK8 and Alzheimer disease: Previous studies have shown that the c‐Jun N‐terminal kinase (JNK) proteins, especially JNK3, a brain‐specific JNK isoform, potentially link together the major pathological hallmarks of AD (Hollos et al., 2020; Sato et al., 2002; Sclip et al., 2014; Sherrin et al., 2010).