ACE2 is downregulated in hepatocellular carcinoma (59), non-small cell lung cancer (NSCLC) (60), breast tumors (61), pancreatic ductal adenocarcinoma (62), and gallbladder cancer (63); ACE2 and TMPRSS2 are both upregulated in colorectal tumor (64) and lung cancer (65). TMPRSS2 is downregulated in head and neck cancer (66). Here, ACE2 is linked to lung cancer.