Collagen, the main building block of skin and tendons, can also contribute to suppressing cancer growth. DDR2, one of the proteins that collagen interacts with, is mutated in some cases of squamous cell carcinoma (SCC) of the lung, a type of non-small cell lung cancer (NSCLC). Researchers have found that when DDR2 is activated by collagen, it in turn activates a protein called SHP-2. It also prevents cell cultures from forming clusters, a model of tumor formation. However, mutant forms of DDR2 that occur in SCC, did not have this effect on cell cultures, and some also did not activate SHP-2, suggesting that lack of SHP-2 activation may contribute to SCC. Drugs that mimic the activity of SHP-2 may offer targeted treatments for SCC.