FURIN and head and neck neoplasm: Accordingly, it has been shown that increased Furin expression correlates with an increase in the processing of membrane matrix metalloproteinase type 1 (MT1-MMP), which is one of its substrates; the latter activates extracellular pro-gelatinase A (a major extracellular matrix-degrading enzyme), which positively regulates tumor growth, thereby increasing the aggressiveness of head and neck tumors [47,48,49].