In conclusion, abnormal expression of Keap1 and Nrf2 proteins was more common than that of the normal oral mucosa and oral epithelial dysplasia tissues, which was significantly related with Prdx6 and CD147, suggesting that Keap1-Nrf2 system and antioxidant enzymes could play an important role together on progression of human oral cancer and might serve as potential target molecules for cancer therapy. This evidence concerns the gene PRDX6 and dysplasia.