PECAM1 and hepatocellular carcinoma: Analysis on the public GSE51401 dataset, which examined the gene expression of CD31+ paired tumor endothelial cells (TECs) and non-tumor endothelial cells (NECs) from 16 HCC patients, indicated that the genes related to leukocyte trans-endothelial migration in TECs was suppressed as comparison with NECs (Additional file 2: Fig. S9B).