It is difficult to decipher which are the key genes involved in the MET/CD44 axis, but IL-8 has been shown to act as an autocrine growth factor in HNSCC, melanoma, and lung carcinoma and addition of recombinant IL-8 can promote directly the proliferation of HNSCC cell lines [51]. This evidence concerns the gene CD44 and head and neck squamous cell carcinoma.