Lysosomal cystine: an unexpected alarm bell for cysteine scarcity

Cells respond to amino acid depletion by activating stress responses. A recent study by Swanda et al. reveals that a decrease in lysosomal cystine triggers a novel stress response that transcriptionally activates ATF4 and protects cells from ferroptosis. A synthetic mRNA, CysRx, can prevent ATF4 activation and enhance antitumor effects.