THBS1 and glioma: While neurite structure was comparably maintained in both conditions (Supplementary Fig. 11c), the number of co-localized pre- and postsynaptic puncta was significantly reduced in SB28-TSP1-KO–neuron co-cultures compared to SB28-TSP1-WT–neuron co-cultures, indicating a role for SB28-TSP1-WT glioma cells in promoting synaptogenesis (mean: 1.23 [WT] vs. 0.56 [KO] per 10 μm neurite; p = 0.004) (Fig. 3b).