![SARS-CoV-2 viral particle with Spike surface protein cleaved and activated by host cellular proteases](https://www2.mrc-lmb.cam.ac.uk/wordpress/wp-content/uploads/LJ_Figure-IR-150x150.jpg)
Scientists had thought that the protease furin was responsible for cleavage of the SARS-CoV-2 Spike protein to reveal the fusion machinery that enables infection, but new work from Leo James’ group shows that furin is not essential for SARS-CoV-2 infection.