AbstractOur previous studies have demonstrated that transforming growth factor e (TGFe) acts as a mitogen for epithelial and fibroblastic cells in both monolayer and soft agar. We have also identified TGFe in both normal and neoplastic tissues of mostly epithelial origin, and in body fluids. In this study we report on the purification of TGFe to homogeneity from bovine kidney using a multistep purification protocol which utilizes high performance electrophoresis chromatography in the final step. Amino acid analysis of TGFe revealed high content of proline, aspartate and glutamate. Examination of partial amino acid sequence indicated no similarity to other, already characterized, growth factors.