Aminopeptidase N (CD13): Bridging physiology, pathology and therapeutic potential.

Aminopeptidase N (CD13) is a multifunctional protein recognized for its diverse roles as an enzyme, receptor, and signalling molecule, attributes that have earned it classification as a "moonlighting" protein. Its involvement in key biological processes such as inflammation, angiogenesis, cell migration, tissue invasion, and the propagation and survival of cancer cells has spurred significant interest in its potential as a therapeutic target. This interest extends beyond oncology to include conditions such as hypertension and rheumatoid arthritis. Consequently, substantial research efforts have been directed toward exploring strategies for leveraging CD13 in clinical interventions. This chapter comprehensively reviews this protein with the aim of improving current understanding of this protein, with a particular focus on its tissue-specific expression and functional roles. Special attention is given to the physiological and pathological diversity of CD13 activity, which offers critical insights into opportunities for selective targeting and disease-specific therapeutic applications.