PECAM1 and hepatocellular carcinoma: Moreover, in tumor tissues from HCC patients treated with PPI, the density of VM structures (PAS+/CD31-) was markedly reduced, accompanied by the downregulation of VM-related markers (VE-cadherin, VEGFR1/2) and EMT markers (Twist1, Vimentin), as well as the upregulation of E-cadherin.