In addition, immunohistochemistry (IHC) staining of platelet endothelial cell adhesion molecule‐1 (PECAM‐1/CD31) and marker of proliferation Ki‐67 (Ki67) suggested that Isg15 KO resulted in attenuated angiogenesis and proliferation in HCC tissues (Figure S5G–J, Supporting Information). This evidence concerns the gene ISG15 and hepatocellular carcinoma.