Oral epithelial cell lines were established in culture from L2D1⁺/p53^+/– and L2D1⁺/p53^–/– mice and all control groups. These were then injected into athymic nude mice and monitored for up to 3 months for tumor development. Tumors contain histologic features of poorly differentiated squamous cell cancer mixed with spindle cells. Depicted are representative photomicrographs of nude mouse tumors from cell lines derived from L2D1⁺/p53^+/– mice. (a) Hematoxylin and eosin staining. (b) Pancytokeratin immunohistochemical staining. (c) Desmin immunohistochemical staining. (d) S-100 immunohistochemical staining. Magnification, ×400.