Two structurally related l-asparaginases are present in the model bacterium Escherichia coli, with their names abbreviated EcAI (for cytoplasmic enzyme) and EcAII (for periplasmic enzyme).Asparaginases from two bacterial sources (EcAII from E. coli and ErA from Erwinia chrysanthemi (Dickeya dadantii)) came to a focus in 1960s–1970s, after being identified as successful agents in treatment of various leukemias and lymphomas, prominently the juvenile non-Hodgkin, lymphoblastic leukemia (ALL)—the most prevalent pediatric cancer (reviewed in2–4). Here, ASPG is linked to acute lymphoblastic leukemia.