CD44 and Alzheimer disease: Second, Alexa FluorTM-labeled tau oligomers derived from AD and DLB brains were transported into cortical neurons isolated from C57BL/6 mice through heparan sulfate proteoglycan (HSPG)-induced, clathrin- and caveolae-independent endocytosis, and remained in endosomes from early endosomes to lysosomes.