Expression of NF1, MAP3K2, PRKCA, NRAS, DUSP3, RAP1A, ATF2, MAPKAPK2, and GRB2 were consistent with the microarray, which suggested that NESG1 participated in the regulation of MAPK pathway in NPC. Four of these relevant genes including ATF2, MAPKAPK2, DUSP3, and GRB2 were selected for further analysis. ATF2 encodes a transcription factor that is a member of the Ponatinib leucine zipper family of DNA-binding proteins. In response to stress stimuli, it activates a variety of gene targets including cyclin A, cyclin D and c-jun, which participate in the oncogenesis of various tissue types. ATF2 expression has been correlated with maintenance of a cancer cell phenotype. MAPKAPK2 is regulated through direct phosphorylation by p38 MAP kinase. In conjunction with p38 MAP kinase, this kinase is known to be involved in many cellular processes including stress and inflammatory response, cell cycle regulation and proliferation. A recent report indicated that MAPKAPK2 could mediate p38 mitogen-activated protein kinase activation to drive invasion of bladder cancer by inducing the expression of MMP-2 and MMP-9. The protein encoded by DUSP3 is a member of the dual specificity protein phosphatase subfamily, which are associated with cellular proliferation and differentiation. Upregulated expression and nuclear localization of DUSP3 promotes the pathogenesis of cervix carcinoma. Loss of the expression can cause cell-cycle arrest and senescence, which was dependent on the hyperactivation of the mitogen-activated protein kinases Jnk and Erk. This effect was reversed by Jnk and Erk inhibition or knock-down. Grb2 knockdown reduced mitogen-activated protein kinase activity in BCR-ABL-expressing hematopoietic cells. Tyrosine phosphorylation of Grb2 is taken as a critical mechanism by which PRL antagonizes EGF-induced cell proliferation by attenuating the activation of the Ras/mitogenactivated protein kinase pathway. Consistent with our microarray results, ATF2, MAPKAPK2, and GRB2 were markedly downregulated while DUSP3 upregulated in NESG1-overexpressing 2F4 NPC cells compared to NESG1-negative C6-Ctr cells. Our results suggested a novel mechanism where dysregulated NESG1 participates in the regulation of MAPK pathway in nasopharynx carcinogenesis. The hypermethylation of CpG islands in gene promoters can often lead to transcriptional silencing of genes, including tumor suppressor genes. Due to the existence of predicted CpG islands in the NESG1 promoter region, we used a NimbleGen DNA methylation microarray to assess its methylation status in 17 NPC cases and 3 NP samples. However, there were no significant changes in NESG1 promoter methylation observed in these samples, suggesting other mechanisms are involved in the repression of NESG1 in NPC. In summary, our present study provides additional support that NESG1 functions as a tumor suppressor in NPC.