LAMP2 and Alzheimer disease: Immunoprecipitation for LAMP-2 (a membrane marker of lysosomes) revealed that more ABCA1 was bound to LAMP-2 in the AD APOE3/4 group than in the NCI APOE3/4 group, indicating that more ABCA1 was trapped in the lysosomes in APOE4 AD (Fig.2F).