According to this study, CEP could usefully protect different cell lines (293T-ACE2, Calu-3, and A549) from infection by different coronaviruses (SARS-CoV, MERS-CoV, and SARS-CoV-2 [S-D614, S-G614, and N501Y variants]) in vitro (Table 2-E) (He et al., 2021). Here, ACE2 is linked to infection.