Glioblastoma (GBM) cells secrete C1QL1, which binds BAI3 on nearby neurons and tumor cells to activate RAC1, promoting tumor microtube growth, malignant synapse formation, and remodeling of normal synapses. Blocking RAC1 with a targeted inhibitor disrupts this process and may help prevent GBM recurrence. See related article by Ding et al., p. 1176.
Li et al. (Mon,) studied this question.