IL-8 is a CXC-chemokine that is activated by interaction with heparan sulfate(51) and that has been shown to directly stimulate osteoclast formation and activity.(32) Importantly, the heparanase-high cells were derived from the osteolytic IL-8 expressing MDA-MET human breast cancer cells.(3,12) As such, the heparanase-high (and heparanase-low) cells also produce significant and measurable levels of human IL-8 (HPSE-High: 78 ± 2 ng/μg of protein; HPSE-Low: 32 ± 5 ng/μg of protein). This evidence concerns the gene CXCL8 and breast cancer.