A second limitation is that we used engineered cell lines that do not represent the full spectrum of virus-cell interactions: the Vero cell line which lacks an interferon response, and the H1299 cell line, having low levels of TMPRSS2 expression, has been shown to be predominantly infected by SARS-CoV-2 through the endocytic pathway43 and therefore would not detect differences in infection through the TMPRSS2-dependent plasma membrane pathway. The gene discussed is TMPRSS2; the disease is infection.