POLB and nasopharyngeal carcinoma: Zheng et al. (2005) explored the role of mutation of the DNA polymeraseβ (polβ) gene in human nasopharyngeal cancer and its relationship with EBV. Zhao (2001) carried out investigation on the mutation of the ras gene and what role they played in HP infection. They determined the infection of HP through serological examination. The results showed that 28 of 43 cases existed with mutations in codon 12 and a mutation rate of 65.12% (Zhao, 2001). Supplementary Figure 1 also shows the relationship between gene mutations and cancers.