Cut off vitamin B7, and some cancer cells lose their metabolic escape plan—revealing a new Achilles’ heel. Credit: AI/ScienceDaily.com Researchers at the University of Lausanne (Unil) have uncovered a new biological mechanism that exposes a critical vulnerability in tumor cells when they are deprived of vitamin B7. All cells must adjust to changes in nutrient supply to survive. However, some cells become especially reliant on glutamine, an amino acid that plays a major role in metabolism.