PTEN and head and neck squamous cell carcinoma: These results strongly indicate that tyrosine kinase dysregulation, particularly EGFR, is an important molecular event in the Tgfbr1/Pten 2cKO mouse model of HNSCC carcinogenesis and the deletion of Tgfbr1 or Pten increased the expression and phosphorylation of total EGFR.