Characterization of normal and tumor endothelial cells. (A) In the immunofluorescence assay, ECs were stained for factor VIII (green) and CD34 (red). The merged image shows yellow and blue areas. (B) qRT-PCR of mRNA expression levels of VEGF in NECs and TECs. The values are expressed relative to NECs (n=3). (C) qRT-PCR of mRNA expression and WB of protein expression levels of PFKFB3 in NECs and TECs. The values are expressed relative to NECs (n=3). (D) Glucose levels in the medium of TECs relative to NECs (n=3). (E) Lactate levels in the medium of TECs relative to NECs (n=3). (F) Glycolytic flux in TECs relative to NECs (n=3). All data are shown as the means ± SEM. *P<0.05. ECs, endothelial cells; TECs, tumor endothelial cells; VEGF, vascular endothelial growth factor; PFKFB3, fructose-2,6-bisphosphatase; NECs, normal endothelial cells.