Tumor growth and tumor vessel density are reduced in β3ΔRGT mice, but not in β3/β1(EGK) mice. β3^+/+, β3^+/−, and β3 mutant mice were inoculated subcutaneously with 300 μL of 2 × 10⁵ B16F1 melanoma cells. (A,C) Quantification of tumor weights 21 days after inoculation. (B,D) Quantification of CD31-positive vessels per field in tumor sections as described in “Methods” (also see supplemental Figure 5C). (E) β3^+/+ or β3ΔRGT mice were transplanted with the indicated bone marrow cells. There were 9-10 transplant recipients/group. Four to 6 weeks later, mice were inoculated with tumor cells and tumor weights were quantified 21 days after inoculation. Data represent means ± SEM. *P < .05; **P < .01; NS, not significant (unpaired Student t test).