Fig. 1

Genes in glycolysis and de novo serine biosynthesis are highly expressed in GBM cells upon serine/glycine deprivation. A U87MG cells were cultured with serine/glycine-containing complete media (S/G( +)) or equivalent media lacking serine/glycine (S/G(-)) for 24 h. B Heatmap presentation of 1,173 genes (fold change ≥ 1.3 and ≤  − 1.3; P < 0.05) in U87MG cells cultured as in (A). C Bubble plot for ontology-based pathway enrichment analysis for DEGs of U87MG cells in S/G-deprived U87MG cells, compared to control. Enrichment score is calculated with odds ratio and P-value and used to rank the pathways. Bubble size indicates odds ratio and is used to assess the strength of association between DEGs and the pathway. Color indicates − log10 (P-value) for determination of the representation significance. THF, tetrahydrofolate; CRF, Corticotropin releasing factor; CCKR, cholecystokinin receptor. D Analysis of trimmed DEGs network with biological functions, including cell proliferation, cell survival, L-serine biosynthetic process, glycolytic process, and glucose import, using IPA in S/G-deprived U87MG cells, compared to control. The analysis involved a fold change cut-off value of ± 1.3. Red and green colors indicate genes that were upregulated and downregulated, respectively, compared to the control. Figure S1A of the SI provides details of shape, which originate from Ingenuity Systems (http://www.ingenuity.com). E Heatmap presentation for gene expression profiles in the L-serine biosynthetic process, glycolytic process, and glucose import. F Schematic of the glucose-derived serine synthesis pathway