Overexpressing AXL in the double-KO HEK293T cells greatly promoted viral infection (Fig. 6d, e), which reached a level similar to that in HEK293T cells overexpressing AXL (Fig. 6a, e), indicating that ACE2 is dispensable in AXL-promoted SARS-CoV-2 virus infection. This evidence concerns the gene AXL and viral infectious disease.