Addition of exogenous furin in the culture media resulted in a dose-dependent increase in both infection (Fig 3A) and GFP-BAP biotinylation, without a concomitant increase in virus uptake (Fig 3B) Conversely, GFP-BAP biotinylation was completely blocked in the presence of biochemical furin inhibitors (Fig 3C) or upon mutation (R9,12K) of the consensus furin cleavage site in L2 (Fig 3D). Here, FURIN is linked to infection.