FN1 and Alzheimer disease: Although different KLK8 substrates, e.g., ephrin receptor B2 (EPHB2) [46], fibronectin [47], neuregulin-1 [48], and the neural cell adhesion molecule L1 (L1CAM) [49], have been long known to be directly involved in the pathophysiology of AD, it was not until recently that the role of KLK8 in the context of AD was recognized.