Usually, high expression levels of ACE2 in tumors, including colon adenocarcinoma (COAD), Kidney renal papillary cell carcinoma (KIRP), pancreatic cancer (PAAD), rectal adenocarcinoma (READ), and lung adenocarcinoma (LUAD), are always accompanied by low DNA methylation level of ACE2.33 Here, ACE2 is linked to lung adenocarcinoma.