A. Western blot of MAT2A-FLAG overexpression in H3K27MPP cells. B. Cell count of H3K27MPP cells comparing combinations of MAT2A over-expression, methionine deprivation, and MAT2A inhibitor. Experiments were performed in biological replicates (n=3). Data is displayed as mean± s.e.m. Statistical analysis performed as two-tailed, unpaired T-test. (H3K27MPP vs. H3K27MPP MAT2A OE *p=0.0285), (H3K27MPP+MR vs. H3K27MPP MAT2A OE+MR ***p=0.0004), and (H3K27MPP+MAT2Ai vs. H3K27MPP MAT2A OE+MAT2Ai **p=0.0013). *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. C. Quantification of SAM in H3K27MPP control and MAT2A over expressing (OE) cells compared with H3WTPP and NSC. Experiments were performed in biological replicates (n=4). Data is displayed as mean± s.e.m. Statistical analysis performed as two-tailed, unpaired T-test. (H3K27MPP vs. H3K27MPP MAT2A OE ****p<0.0001), (H3K27MPP vs. H3WTPP **p=0.0012), and (H3K27MPP vs. NPC **p=0.001). *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. D. Cell count of H3K27MPP cells comparing combinations of MAT2A Inhibitor (AGI-24512), AMD1 inhibitor (SAM426) and methionine deprivation conditions. Experiments were performed in biological replicates (n=3). Data is displayed as mean± s.e.m. Statistical analysis performed as two-tailed, unpaired T-test. (H3K27MPP+MR vs. H3K27MPP+MR+AMD1i **p=0.0016). E. Quantification of SAM in H3K27MPP cells comparing the combination of AMD1 inhibitor (SAM426) with methionine deprivation conditions. Experiments were performed in biological replicates (n=4) Data is displayed as mean± s.e.m. Statistical analysis performed as two-tailed, unpaired T-test. (H3K27MPP vs. AMD1i ***p=0.0003), (H3K27MPP vs. MR ***p=0.0002), and (H3K27MPP+MR vs. H3K27MPP+MR+AMD1i **p=0.0089). *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001.