(44) provided evidence that SARS CoV-2 S protein RBD also binds to broadly expressed integrin α5β1 with high affinity, the binding could be mediated by the S protein LDI motif, which enables SARS CoV-2 to infect ACE2 negative cells upon integrin activation after the initial ACE2 mediated infection of the lung epithelium. Here, ACE2 is linked to infection.