In addition, astrocytes are known to secrete NGF and BDNF (reviewed in the study by Albini et al.82)in response to injury or neuronal activity, and these neurotrophins have been shown to support tumor cell survival, invasion, and EMT in several cancers, including head and neck squamous cell carcinoma, and glioma.83 This evidence concerns the gene BDNF and head and neck squamous cell carcinoma.