GLS and cancer: When asparaginase therapy was introduced in the treatment of cancer it became obvious that this bacteria-derived enzyme had other effects, one of the most significant is immunosuppression, which is regarded to be in association with its glutaminase activity.6 Immune cells require substantial amounts of glutamine to sustain its proliferation and functions, whereas all the asparaginases possess some degree of glutaminase activity, which hydrolyzes the amino acid glutamine.40