Additional administration of recombinant IL-6 into B16-F10 tumor-bearing IL-17−/− mice results in markedly increased tumor size and p-Stat3 expression, whereas additional recombinant IL-17 administration into B16-F10 tumor-bearing wild-type mice treated with anti-IL-6 mAb does not significantly alter the tumor growth and p-Stat3 expression. The gene discussed is IL17A; the disease is neoplasm.