KDR and neoplasm: However, unlike those models, the growth of orthotopically inoculated Line IV Cl 1 melanoma cells is not affected by SLT-VEGF, indicating that either the level of depletion of VEGFR-2+/CD31+ cells was not sufficient to inhibit tumor progression or that the contribution of VEGFR-2+/CD31+ endothelial cells to tumor progression is not critical in this model.