RAC1 and central nervous system cancer: Semaphorin 5A and its receptor plexin-B3, however, have been shown to significantly inhibit glioma cell migration and invasion, with concomitant inactivation of Rac1 through RhoGDIα and the promotion of glioma cell differentiation; semaphorin5A protein expression was significantly reduced in high-grade astrocytomas (60, 61).