PECAM1 and cancer: In addition, IHC staining of HMGA2, Snail, CD31, TJ proteins, α-SMA, Vimentin and S100A4 in a series of sections of primary NPC specimens showed that the expression of HMGA2 in tumors was negatively correlated with CD31 and TJ protein expression but positively correlated with Snail, α-SMA, Vimentin and S100A4 expression in endothelial cells (Supplementary Fig. S12), thus supporting the functional association of HMGA2 in tumor cells with endothelial cell barrier destruction and formation of a microenvironment conduce to cancer metastasis.