Scientists discover backup cysteine production pathway in mammalian cells

Scientists have identified a previously unknown cellular survival pathway that enables mammalian cells to synthesize the essential amino acid cysteine even when the pathways once considered indispensable are disabled, a finding described as “impossible” by the researchers.

The discovery reveals a backup system that maintains cysteine production, a function that may also allow cancer cells to resist treatment. Researchers suggest that targeting this alternative mechanism could make tumors easier to kill by removing the cells’ ability to survive without the primary cysteine‑making routes.

The study highlights a novel survival route in mammalian cells that could be exploited to improve cancer therapy.