DKK3 and head and neck squamous cell carcinoma: In fact, DKK3 protein expression is high in HNSCC, and DKK3 exerts oncogenic function via activation of Akt, and inhibition of DKK3 or its receptor, cytoskeleton-associated protein 4 (CKAP4), by antibodies resulted in significantly decreased cellular proliferation, migration, and invasion [10–15].