Currently, we have been making efforts to develop a sensitive and reliable assay for soluble IL-6/IL-6Rα complex in order to study the relationship between IL-6, IL-6Rα and IL-6/IL-6Rα complex expressed and released by cultured NPC cells of primary and metastatic tumor origins under IFN-γ-transduced and nontransduced conditions. The gene discussed is IL6R; the disease is metastatic neoplasm.