CPA4 is a member of the carboxypeptidase A/B subfamily. Carboxypeptidases are zinc-containing exopeptidases that catalyze the release of carboxy-terminal amino acids, and are synthesized as zymogens that are activated by proteolytic cleavage. This protein could be involved in the histone hyperacetylation pathway. It is imprinted and may be a strong candidate protein for prostate cancer aggressiveness.