 Studies with mice have shown that knocking out ApoER2 or just the alternatively spliced exon 19 causes a much greater impairment of LTP than knocking out VLDLR.Apolipoprotein E (ApoE) plays an important role in phospholipid and cholesterol homeostasis.After binding ApoER2, ApoE is taken up into the cell and may remain in the intracellular space, be shipped to the cell surface, or be degraded.