CTH and glioblastoma: The importance of CSE as a source of cysteine for GSH production is well established in astrocytes20,21 and an early study in C6 glioma cells showed that CSE expression increases upon GSH depletion.32 However in IDHwt GBM, the expression of CSE is variable, suggesting a more plastic response to cysteine depletion, which is consistent with the specific sensitivity to CSE inhibition that we found in IDHm versus IDHwt cells.