Lymph endothelial cells secrete chemokines including chemokine (C-X-C motif) ligand 12 (CXCL12) and chemokine (C-C motif) ligand 21 (CCL21) to recruit tumor cells that express chemokine (C-C motif) receptor 7 (CCR7) and chemokine (C-X-C motif) receptor 4 (CXCR4) [95, 96]. The gene discussed is CCL21; the disease is neoplasm.