text: Cancer-based research into co-receptors includes the investigation of growth factor activated co-receptors, such as Transforming Growth Factor (TGF-β) co-receptors. Expression of the co-receptor endoglin, which is expressed on the surface of tumor cells, is correlated with cell plasticity and the development of tumors.
  Another co-receptor of TGF-β is CD8.  Although the exact mechanism is still unknown, CD8 co-receptors have been shown to enhance T-cell activation and TGF-β-mediated immune suppression.
  TGF-β has been shown to influence the plasticity of cells through integrin and focal adhesion kinase. The co-receptors of tumor cells and their interaction with T-cells provide important considerations for tumor immunotherapy.
  Recent research into co-receptors for p75, such as the sortilin co-receptor, has implicated sortilin in connection to neurotrophins, a type of nerve growth factor.
  The p75 receptor and co-receptors have been found to influence the aggressiveness of tumors, specifically via the ability of neurotrophins to rescue cells from certain forms of cell death. 
  Sortilin, the p75 co-receptor, has been found in natural killer cells, but with only low levels of neurotrophin receptor. The sortilin co-receptor is believed to work with a neurotrophin homologue that can also cause neurotrophin to alter the immune response.