ACE2 and COVID-19: By studying the susceptibility of different cell lines from induced stem cells, pancreatic and liver cells have been identified as being more susceptible to infection by SARS-CoV-2; on the other hand, cells that express ACE2—such as the endothelium, macrophages, and cortical neurons—show low or no permissiveness for the SARS-CoV-2 virus, suggesting that the nonlinear relationship between ACE2 and the permissiveness to SARS-CoV-2 infection highlights the importance of using pluripotent stem cells in place of cells that overexpress ACE2 to study the biology of SARS-CoV-2 [46].