JAK2 and nasopharyngeal carcinoma: This discrepancy is very likely to involve the differences in the utility of factors, such as JAK1, JAK2, JAK3, Tyk2, NF-κB, IFN regulatory factor 1 (IRF-1) and/or STATs (e.g. STAT-1 activated by IFN-γ; STAT-3 activated by IL-6), thereby creating a positive and a negative regulation for P-NPC and BM-NPC cells respectively [47].