RAB27A and glioma: To assess the consequences of Rab27a/b deletion in vivo, we engrafted GL261 syngeneic (GBM-like) glioma cells intracranially into the right striatum of either WT, dHET, or dKO mice (Fig. 2A) and monitored tumor progression and vascularity (Fig. 2, B to G, and fig.