C4B and Alzheimer disease: When looking at specific genes, mouse astrocytes upregulate Gfap, Bcl3, Serpina3n, Cyb5r2, Chil4, Bdkrb2, Rnase4 and the complement cascade genes C4a, C4b in AD model mice (PS2APP and APP/PS1) compared to control mice [134,135] (Table 1).