Dysplasia scores are depicted for wild-type, p53+/–, L2D1+/p53+/+, and L2D1+/p53+/– mice for tongue, mouth, upper esophagus, and lower esophagus tissues at 3, 6, and 12 months (a). The same scoring system is represented for L2D1+/p53–/– and p53–/– mice at 5 months (b). Scores for the L2D1+/p53+/– group were significantly different from control scores at 6 and 12 months. Scores for the L2D1+/p53–/– mice were significantly different from controls at 5 months. P < 0.05. WT, wild-type.