Every cell in the body displays fragments of the proteins it is making on its surface, like a shop putting samples in the window. Immune cells patrol past, reading those samples. When a cell is making something abnormal, a cancer protein or a viral protein, the display is what gets it killed.
Researchers at Rockefeller University report that a single amino acid controls how well that display works. When arginine runs short, production of the display molecules stalls, and cells become harder for the immune system to see.
