ACE2 and COVID-19: Given that initial SARS-CoV-2 infection via ACE2 in the respiratory system is known to generate cytokines (28) that can activate integrins (29, 30, 31), our data suggest that more SARS-CoV-2 particles may enter into (via the activated integrin) various human cells and tissues especially those lacking ACE2 thereby contributing to further infection and progression of COVID-19.