ASS1 and neoplasm: In contrast, U87 NS displayed upregulation of ASS1 and concomitant downregulation of ASL, ODC1, SLC25A13 and SLC25A15. Thus, it can be concluded that NS cultures of NCH644 cells recapitulate some of the metabolic features also found in human tumours and may therefore represent a suitable model to study metabolic reprogramming in GSCs.