Metallocarboxypeptidases (MCPs) excise one amino acid at a time from the C-terminal ends of polypeptides and are important for digestion, as exemplified by bovine pancreatic carboxypeptidases A and B. MCPs are subdivided into the A/B subfamily (M14A according to MEROPS), the N/E subfamily (M14B), the γ-d-glutamyl-mesodiaminopimelate peptidase I (M14C), and the complex cytosolic carboxypeptidases, CCPs (M14D). These enzymes are expressed in all tissues and likely play a role in processes such as the maturation of neuropeptides, hormones, and cytokines, in blood fibrinolysis, and in anaphylaxis. MCPs may also be involved in harmful processes such as fibrinolysis and inflammation, and may contribute to the pathology of Alzheimer's disease (AD) and cancer.