Atrial natriuretic factor (NPPA(124-151) aka ANF) is a cardiac hormone essential for the regulation of blood pressure and promoting natriuresis, diuresis and vasodilation. In cardiac myocytes, NPPA is synthesised as an inactive precursor, pro-NPPA, that is converted to the biologically-active form by cleavage. Atrial natriuretic peptide-converting enzyme (CORIN) is the serine-type endopeptidase involved in NPPA processing. It is itself cleaved into 5 chains, with CORIN(802-1042) being the activated protease fragment (Yan et al. 2000, Knappe et al. 2003, Liao et al. 2007).