ROBO4 and Alzheimer disease: Similarly, astroglia in Subcluster 2 (147 cells vs. 198 cells) appeared to be activated, based on the upregulation of cx43, predicted to be the top key driver of an astrocyte enriched subnetwork associated with AD and which regulates the expression of more than half of known AD risk factor genes mt2, robo4, cspg5a, cspg5b, and cxcl14.