CDC42 and cancer: To determine the underlying mechanism by which EMP1 and copine-III promote cell migration, we examined Rac1 activity by the pull-down assay using glutathione beads bound to GST-p21-activated kinase1 (PAK)-Cdc42 and Rac-binding domain (CRIB), as Rac1 essentially activates cell migration and cancer metastasis [19].