NPPB, also known as B-type natriuretic peptide (BNP), is a cardiac hormone that is secreted mainly in the ventricles in response to increased wall stress. The protein undergoes two cleavage events, one within the cell and a second after secretion into the blood. The protein's biological actions include natriuresis, diuresis, vasorelaxation, inhibition of renin and aldosterone secretion, and a key role in cardiovascular homeostasis. BNP is a marker of systolic and diastolic dysfunction and a strong predictor of mortality in heart failure patients.