NGF has shown to play a role in tumour proliferation and in perineural invasion in ex vivo and in vitro studies where a tissue of OSCC and human oral cancer cells has been used to investigate the expression of NGF and the concentration of NGF protein, respectively, and the results showed that the tissue biopsies from OSCC showed a strong NGF immunoreactivity and that NGF protein concentration was higher in oral cancer cells than in normal cells [138]. Here, NGF is linked to lip and oral cavity carcinoma.