Asparaginase (L-ASNase) of Escherichia coli origin is a universal component of therapy for acute lymphoblastic leukemia.16 L-ASNase catalyzes the deamination of asparagine to aspartate and to a lesser extent the deamination of glutamine to glutamate.17 Both activities may be needed for therapeutic effectiveness against malignancies.17,18 Asparagine depletion leads to an adaptive response in which uncharged tRNA activates the serine/threonine kinase GCN2 (ref. 19). Here, ASPG is linked to acute lymphoblastic leukemia.