 The phosphorylated Dab1 then causes further activation of these two kinases and others, including a phosphatidylinositol-3-kinase (PI3K).PI3K activation leads to inhibitory phosphorylation of the tau kinase glycogen synthase kinase 3 beta (GSK3B), which alters the activity of tau protein, a protein involved in stabilizing microtubules.This transduction is combined with the activation of other pathways that influence the cytoskeletal rearrangement necessary for proper cortical cell migration.