When BEL-7404 cancer cells were infected with Ad5-hSulf1 to re-express hSulf-1 and then transfected with VEGFR-2 shRNA to silence VEGFR-2 expression, the cell viability was further decreased, exactly demonstrating that there is another mechanism involved in VEGFR-2 activation and cancer cell proliferation in the context of hSulf-1 effect. This evidence concerns the gene KDR and cancer.