CD4 (cluster of differentiation 4) is a molecule that is expressed on the surface of T helper cells (as well as regulatory T cells and dendritic cells). On T cells, CD4 is the co-receptor for the T cell receptor (TCR) and recruits the tyrosine kinase lck. Cluster of Differentiation (CD) molecules are markers on the cell surface, as recognized by specific sets of antibodies, used to identify the cell type, stage of differentiation and activity state of a cell. ... T cells are a subset of lymphocytes that play a large role in the immune response. ... This article or section should be merged with suppressor T cell Regulatory T cells (also known as suppressor T cells) are characterised by virtue of their expression of the cell surface markers CD4 and CD25. ... Dendritic cells (DC) are immune cells and form part of the mammal immune system. ... TCR can stand mean: Toronto Civic Railways Tottenham Court Road, a street in London which Tottenham Court Road tube station is named after A single by the band Prolapse T cell receptor A joint venture between Brambles Industries and German airport company Fraport AG This is a disambiguation page — a... Tyrosine kinases are a subclass of protein kinase, see there for the principles of protein phosphorylation A tyrosine kinase (EC 2. ...