ACE2 and viral infectious disease: To confirm Rpb1 degradation in the context of NL63 infection, we used Vero E6-TMPRSS2-T2A-ACE2 (VeroE6-TA), 293T-ACE2, and LLC-MK2-ACE2 cells, all of which overexpress human ACE2 (the receptor for NL63) and are susceptible to viral infection.