TP53 and cancer: These include chemical-induced cancer models; syngeneic murine cancer cells injected back into immunocompetent mice from the same strain; transgenic mice expressing mutant KRAS[5,6] or activated AKT with p53 loss [7]; and xenograft models in which human HNSCC cell lines, grown on plastic in tissue culture, are injected into immunocompromised mice, either subcutaneously or into an orthotopic site such as the tongue or the floor of the mouth [8].