C-C chemokine receptor type 7
C-C chemokine receptor type 7 is a protein that in humans is encoded by the "CCR7" gene. Two ligands have been identified for this receptor: the chemokines (C-C motif) ligand 19 (CCL19/ELC) and (C-C motif) ligand 21 (CCL21). CCR7 has also recently been designated CD197 (cluster of differentiation 197). Function. The protein encoded by this gene is a member of the G protein-coupled receptor family. This receptor was identified as a gene induced by the Epstein-Barr virus (EBV), and is thought to be a mediator of EBV effects  on B lymphocytes. This receptor is expressed in various lymphoid tissues and activates B and T lymphocytes. CCR7 has been shown to stimulate dendritic cell maturation. CCR7 is also involved in homing of T cells to various secondary lymphoid organs such as lymph nodes and the spleen as well as trafficking of T cells within the spleen. Activation of Dendritic cells in peripheral tissues induces CCR7 expression on the cell's surface, which recognize CCL19 and CCL21 produced in the Lymph node and increases dendritic cell expression of co-stimulation molecules (B7), and MHC class I or MHC class II . Clinical significance. CCR7 is expressed by various cancer cells, such as nonsmall lung cancer, gastric cancer and oesophageal cancer. Expression of CCR7 by cancer cells is linked with metastasis to lymph nodes.