These genes include KANK1 that regulates actin-mediated migration and RhoA activity [64]; ApoE, a well-studied gene in the context of Alzheimer disease, that mediates cerebrovascular pericyte mobility through RhoA [65]; and PREX1, a guanine nucleotide exchange factor for the RHO family that functions as RAC 1 activator and is also involved in neuronal migration [66]. The gene discussed is PREX1; the disease is Alzheimer disease.