CCL21 and breast cancer: Since the observed effects of heparin mimetics depend on interactions with a variety of growth factors as well as pro-metastatic biological factors (such as the CXCL12-CXCR4 axis, CCR7-CCL21 axis), it is possible that these angiogenic and metastatic factors are common to the majority of breast cancer types, thus making heparin and heparin mimetics potential therapeutic agents for most types of breast cancer.