FURIN is a ubiquitously expressed proprotein convertase that cleaves dibasic and polybasic amino acid motifs in precursor proteins to generate mature, active forms 1. Primary functions include processing TGF-β signaling components, with mutations impairing pro-TGF-β maturation and downstream SMAD2 phosphorylation, affecting aortic structural integrity 2. FURIN also processes viral glycoproteins critical for pathogenic infection—notably cleaving SARS-CoV-2 spike protein at the S1/S2 junction to facilitate viral entry 1, and processing mumps and Ebola envelope proteins 3. Clinically, rare FURIN variants predispose to aortic aneurysms, with 3.7% of aneurysm patients carrying heterozygous variants that reduce enzyme activity and impair collagen/fibrillin organization 2. FURIN expression correlates with COVID-19 severity—elevated sputum levels associate with neutrophilic asthma and inflammasome activation, increasing COVID-19 mortality risk 4. FURIN gene polymorphisms (rs6226) independently predict severe COVID-19 outcomes and susceptibility in certain populations 5. Additionally, FURIN-mediated apelin maturation promotes colorectal cancer metastasis, making proapelin cleavage-site inhibition a therapeutic strategy 6. FURIN inhibition represents a promising therapeutic target since somatic cell knockout is viable, while germline loss is embryonic lethal 1.