Antibodies against vWF and CD31 have failed to stain sinusoid endothelial cells in many HCC cases, whereas CD34 has proven to be a more sensitive and specific endothelial cell marker for microvessels in HCC (McComb et al. 1982; Simmons et al. 1990; Ruck et al. 1995). The gene discussed is PECAM1; the disease is hepatocellular carcinoma.