CCR7 and cancer: We also demonstrated that activation of TAK1 up-regulates the expression of chemokine (C-C motif) receptor 7 (CCR7) and increases the lymphatic invasion ability of breast cancer cells because lymphatic endothelial cells (LECs) express high level of CCR7 ligands CCL19 and CCL21 and induce a chemotactic effect on CCR7-expressing cancer cells.