MKI67 and hepatocellular carcinoma: 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).