Expression of genes involved in angiogenesis in Del-1 HUVEC versus eGFP HUVEC. (A) Del-1 HUVEC expressed much higher levels of Del-1 mRNA compared with eGFP HUVEC. (B) When cultured on TCPS for 7 days, Del-1 HUVEC differentially expressed Ang2, VEGF-A, ICAM-1, PLAU, and MMP-9 compared with eGFP HUVEC. Differences were small, but statistically significant (at least at p<0.1). (C) When cultured on collagen, MMP-9 was upregulated in Del-1 HUVEC compared with eGFP HUVEC. Data are presented as ratios of relative gene expression (Del-1 HUVEC vs. eGFP HUVEC, relative to GAPDH). Graphs show average of ratios±SEM; N=3; paired t-test one tailed with p<0.05 (*) or p<0.10 (**) and 0.67≤Ratio ≥1.5 highlighted. Ang2, angiopoietin-2; ICAM-1, intercellular adhesion molecule-1; MMP-9, matrix metalloproteinase-9; TCPS, tissue culture-treated polystyrene; uPA, urokinase-type plasminogen activator; VEGF-A, vascular endothelial growth factor.