BDNF and cancer: Using the 4NQO carcinogen-induced model of oral squamous cell carcinoma (OSCC), Valente et al. have shown that baseline levels (prior to 4NQO exposure) of NE, cortisone and neurotrophins such as brain-derived neurotrophic factor (BDNF) in normal tongue can be predictive of cancer occurrence in rats exposed to 4NQO [22].