CD9 and Alzheimer disease: At transcriptional level, microglia from the APOE4 group upregulated several DAM markers (Cd74, Cst7, Cd63, Cd9, Ccl6), complement cascade genes (C1qa, C1qb, C1qc) and the pro-inflammatory gene Nfkbia (Sousa et al, 2018), similar to transcriptomic changes in microglia from APOE4 AD individuals (Serrano-Pozo et al, 2021).