AGRN and Alzheimer disease: Furthermore, some proteins enriched in AD samples were shown to trigger Aβ fibrillation, such as syndecan-4 (SDC4) [72] and agrin [65], or, in contrast, increase the solubility of amyloid peptides such as SAP [73] and inhibit Aβ aggregation, such as HSPB1 [74] and MT3 [75].