In addition, amongst the TG2 interactors common for APP23 and WT is the well-known AD risk factor and key player in both Aβ-pathophysiology and AD-related neurodegeneration [49,50], Apolipoprotein E (ApoE), which we recently identified as a substrate for TG2-catalyzed crosslinking [21]. Here, APOE is linked to Alzheimer disease.