Anti-KDR peptide induced significant apoptosis of HUVECs relative to controls (141±7% vs control, P<0.05) but had no effect on tumour cell apoptosis in murine and human tumour cells (4T1, 77.12±20.82%; MDA-MB-231, 86.24±5.61% vs control), consistent with the lack of expression of Flk-1/KDR in these cells. This evidence concerns the gene KDR and neoplasm.