We found increased numbers of specimens positive for Ki67 staining as the histopathological diagnosis rose in severity from normal mucosa (1/33%), to epithelial hyperplasia and chronic inflammation (4/44.4%), through epithelial dysplasia and carcinoma in situ (9/81.8%), and oral squamous cell carcinoma (24/88.9%) (Table 6). The gene discussed is MKI67; the disease is intraepithelial neoplasia.