PTEN and head and neck squamous cell carcinoma: HNSCC tumorigenesis by deletion of Pten (Pten cKO mice), Tgfbr1 (Pten cKO mice with DMBA), and combined deletion of Tgfbr1 and Pten (Tgfbr1/Pten 2cKO mice) has already been reported [27].