To examine whether GDF3 promotes tumorigenesis of not only GDF3-expressing B16 melanomas but also tumors with no expression of GDF3, we transfected the mouse hepatoma G1 or G5 cell lines with empty or GDF3-expressing vectors, and injected the transfected cells into inbred BALB/c mice. The gene discussed is GDF3; the disease is hepatocellular carcinoma.