Uptake of extracellular asparagine prevents the death of glioblastoma cells in response to glutamine depletion by blocking the apoptotic function of a glutamine-induced endoplasmic reticulum stress marker protein, ATF4, and by increasing glutamate-ammonia ligase (GLUL)-mediated glutamine and protein synthesis116,117. The gene discussed is GLUL; the disease is glioblastoma.