TRAF6 and head and neck squamous cell carcinoma: In line with the in vivo data, knockdown of TRAF6 or inhibition of TRAF6 E3 ligase activity suppresses the survival, proliferation, migration, and metastasis of many human epithelial cancers, including breast, lung, liver, and colon cancers as well as HNSCC (230–232, 236–240).