Specifically, Vero cells only possessing the cathepsin entry route, VeroTMPRSS2 cells containing both cathepsin and TMPRSS2 protease, and Calu-3 cells, which are lung cells previously found to completely rely on the TMPRSS2 protease for VSV-eGFP-SARS-CoV-2 (24, –26), were found to have complete inhibition of infection in the presence of 10 nM of longHR2_42 (SI Appendix, Fig. S3). Here, CTSS is linked to infection.