HGF and head and neck squamous cell carcinoma: Various CAF-secreted factors, have been implicated in promoting HNSCC invasion and/or proliferation, including IL-1β (interleukin 1β) [42], activin A [43], HGF (hepatocyte growth factor) [44] and EREG (epiregulin) [45], which has additionally been suggested to play an autocrine role in CAF activation [45].