To investigate the spatial relationship between breast cancer cells, endosteal surfaces and bone microvessels, 30 μm thick tibial sections of long bones, isolated from 6-week and 12-week old animals 6 days following tumour cell injection, were stained with antibodies against endomucin (a pan-endothelial marker to visualise the entire capillary network), the bone marker osteopontin and human CD29 and CD59 (markers expressed on the human tumour cells). This evidence concerns the gene CD59 and breast cancer.