a, Western blotting analysis on the protein lysate of GBM BTIC (pGBM-rGBM matched and unmatched samples) confirmed a two-fold increase in OAS2 expression. b, BT972, an OAS2 high expressing recurrent GBM BTIC line, was used for functional analysis. OAS2 was knocked out using CRISPR knockout gene editing. Following confirmation of gene knockout (construct A, B and C) by western blotting, the effect of OAS2 on self-renewal and proliferation capacity of OAS2 KO BT972 vs OAS2 WT BT972 (BT972 AAVS1) were measured using secondary sphere formation assay and PrestoBlue proliferation assay, respectively (P value: *** p < 0.001, **** p < 0.0001) (One way ANOVA). c-d, OAS2 KO BT972 and BT972 control (BT972 AAVS1) (100,000) were intracranially implanted into the right frontal lobe of NSG mice (n=6). The tumor size was tracked weekly using MRI imaging. e, IHC analysis of IBA1 on GBM xenografts from OAS2 KO or WT GBM cell engrafted mice revealed higher levels of IBA1 expression in OAS2 WT vs OAS2 KO engrafted brains. Scale bars represent 100 μm.