MUC4 and infection: The StcE-mediated digestion of extracellular mucins in MUC4 and MUC1 GOF as well as NTG cell lines led to a dramatic increase in VSV-CoV-2-S infection compared with untreated cells, indicating that mucin removal renders cells more permissive to VSV-CoV-2-S infection, consistent with our in vivo data (Fig. 7c,e and Extended Data Fig. 9a).