Furthermore, a direct correlation between the expression levels of MTH1, OGG1, MUTYH, and EBNA1 was detected in sublines of the EBV positive BL Mutu and higher levels of MHT1 were detected in western blots of four out of five EBV converted sublines of EBV-negative Burkitt lymphoma, gastric carcinoma and nasopharynx cancer while OGG1 and MUTYH exhibited a somewhat less consistent pattern of regulation (Fig. 4). This evidence concerns the gene NUDT1 and malignant tumor of nasopharynx.