Figure 3.

Breast cancer cells home to the bone microenvironment. Bone is made up of different cell types that express a variety of molecules including the chemokine CXCL12 that attract breast cancer cells to this microenvironment. Breast cancer cells also express molecules including the chemokine receptor CXCR4 that enable them to adhere to the osteoblast-rich HSC cell niche and disseminate in the bone. Once in the bone microenvironment, tumour-derived growth factors prime the bone for subsequent colonisation of tumour cells. OPN, osteopontin; HPSE, heparanase.