GPLD1 and Alzheimer disease: Furthermore, phospholipase D (PLD), particularly PLD1, plays a role in amyloidogenesis by affecting PC metabolism, influencing the cell surface delivery of amyloid precursor protein (APP) and presenilin-1 (PS1) and modulating PS1 activity, both of which are critical processes in AD development (Garner, 2010; Cai et al., 2006a; Cai et al., 2006b).