This difference in metastatic tumor location was attributed to the expression of transforming growth factor-beta 2 (TGF-β2) in cancer cells: TGF-β2 mRNA was highly expressed by the K-1735 cells, whereas the B16 cells or B16 x K-1735 cell mixes had low expression. This evidence concerns the gene TGFB2 and metastatic neoplasm.