We have previously established that ET-1 can be degraded in vivo by two lysosomal/secreted serine carboxypeptidases, Cathepsin A (CathA) and Serine Carboxypeptidase 1 (Scpep1) and that gene-targeted CathAS190A/Scpep1-/- mice, deficient in CathA and Scpep1 have a prolonged half-life of circulating ET-1 associated with systemic hypertension. The gene discussed is EDN1; the disease is Hypertension.