Macrophages are known producers of apolipoprotein, and in vitro challenge of macrophages from AD transgenic mice expressing the three major isoforms of APOE indicates that the APOE2 allele may confer an enhanced ability to phagocytose Aβ on myeloid cells associated with increased expression of MMP-9 [118]. The gene discussed is APOE; the disease is Alzheimer disease.