RAC1 and glioma: The mammalian homolog, MEGF10, is required for glial clearance of apoptotic neurons, as well as developmental axonal/synaptic pruning.4, 5, 10, 11, 12, 13, 14, 15, 16, 20, 44, 45, 46, 47, 48, 49, 50 The high conservation of GEF/Rac1-mediated control of cell migration is also well documented.51, 52, 53, 54 Our work now reveals that the PP4 phosphatase complex unifies these two conserved molecular signaling pathways in the context of glial immunity and may also provide new molecular insight into glial tumor cell migration.