These observations reinforce the concepts developed in the case of the collagen VI null mouse, the NG2 null mouse, and the Tks5 knockdown mammary tumors; namely, that reduced deposition of the vascular basement membrane results in loss of sequestration of VEGF-A in close proximity to tumor vessels, with negative consequences for vessel structure and function, as well as for tumor growth. The gene discussed is SH3PXD2A; the disease is breast cancer.