DDR1 and head and neck squamous cell carcinoma: Having shown that HNSCCs exist in a collagen-rich environment, we examined the effects of exogenous type I collagen, which is frequently used as an activator of DDR1, on the behaviour of HNSCC cell lines (SCC040, SCC154, VU040T and VU147T) using assays of cell growth, migration and response to chemotherapy in vitro.