Dipeptidase 1 (DPEP1) is a kidney membrane enzyme that belongs to the peptidase M19 family. DPEP1 is a homodimer and is inhibited by L-penicillamine. DPEP1 hydrolyzes a variety of dipeptides and is implicated in renal metabolism of glutathione and its conjugates. DPEP1 is responsible for hydrolysis of the beta-lactam ring of antibiotics, such as penem and carbapenem. DPEP1 may play an important role in the regulation of leukotriene activity. DPEP1 expression in cancer is significantly higher than that in normal tissue. However, DPEP1 expression decreased with pathological differentiation, lymph-node and distant metastasis.