Inhibition of angiogenesis within tumors. BALB/c mice were immunized with pORF-hFlk-1 LDC, pORF-mFlk-1 LDC, pORF-mcs LDC or GS once a week for 6 weeks. The mice were then inoculated with 2 × 105 CT26 tumor cells. Frozen sections of tumor tissue were tested by immunohistochemical analysis with anti-CD31 antibody (A-D). Vessel density in tumor tissues from human VEGFR-2 LDC immunized mice indicated a significant decrease compared with controls (I; P < 0.01). Columns: means; bars: SD. Vascularization of alginate implants. Mice were immunized as above and alginate beads containing 1 × 105 CT26 tumor cells per bead were then implanted s.c. into the backs of mice 7 days after the last immunization. Beads were surgically removed 12 days later (E-H), and FITC-dextran was quantified (J). Bead uptake in mice immunized with human VEGFR-2 LDC showed a significant decrease compared with controls (P < 0.01). Columns: means; bars: SD.