As a protein convertase, furin cleaves immature NOTCH protein to its mature heterodimeric form prior to surface expression (van Tetering and Vooijs, 2011), and also cleaves SARS-CoV-2 spike protein in a process required for its efficient cellular entry during infection (Peacock et al., 2021; Wu and Zhao, 2021). This evidence concerns the gene FURIN and infection.