FN1 and Alzheimer disease: With respect to AD pathology, there are some interesting ligands for the LILRB2-4 receptors; i.e., (i) Aβ1–42 (Aβ42) oligomers target LILRB2 [87, 98], and (ii) ApoE4 is a ligand for LILRB3 [86], whereas (iii) ApoE and fibronectin are ligands for the LILRB4 receptor [85, 99, 100].